v3.26.1
Feb. 28, 2026
MFS Active Core Plus Bond ETF
Risk Table - MFS Active Core Plus Bond ETF
Risk [Text Block]
Principal Risks

Principal Risks

As with any exchange-traded fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.

The principal risks of investing in the fund are:

Risk Lose Money [Member] As with any exchange-traded fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund.
Risk Not Insured [Member] An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.
Investment Selection Risk

Investment Selection Risk: MFS' investment analysis and its selection of investments may not produce the intended results and/or can lead to an investment focus that results in the fund underperforming other funds with similar investment strategies and/or underperforming the markets in which the fund invests. In addition, to the extent MFS considers quantitative tools in managing the fund, such tools may not produce the intended results.

Debt Market Risk

Debt Market Risk: Debt markets can be volatile and can decline significantly in response to changes in, or investor perceptions of, issuer, market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. These conditions can affect a single instrument, issuer, or borrower, a particular type of instrument, issuer, or borrower, a segment of the debt markets or the debt markets generally. Certain events can have a dramatic adverse effect on debt markets and may lead to periods of high volatility and reduced liquidity in a debt market or segment of a debt market.

Interest Rate Risk

Interest Rate Risk: In general, the price of a debt instrument falls when interest rates rise and rises when interest rates fall. Interest rate risk is generally greater for instruments with longer maturities or durations, or that do not pay current interest.

Credit Risk

Credit Risk: The price of a debt instrument depends, in part, on the credit quality of the issuer, borrower, counterparty, or other entity responsible for payment, or underlying collateral or assets and the terms of the instrument. The price of a debt instrument can decline in response to changes in, or perceptions of, the financial condition of the issuer, borrower, counterparty, or other entity, or underlying collateral or assets, or changes in, or perceptions of, specific or general market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. Debt instruments may be more susceptible to downgrades or defaults during economic downturns or similar periods of economic stress, which in turn could negatively affect the market value and liquidity of a debt instrument.

Below investment grade quality debt instruments (commonly referred to as “high yield securities” or “junk bonds”) can involve a substantially greater risk of default or can already be in default, and their values can decline significantly. Below investment grade quality debt instruments are regarded as having predominantly speculative characteristics. Below investment grade quality debt instruments tend to be more sensitive to adverse news about the

issuer, or the market or economy in general, than higher quality debt instruments.

Foreign Risk

Foreign Risk: Exposure to foreign markets through issuers or currencies can involve additional risks relating to market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. These factors can make foreign investments, especially those tied economically to emerging markets or countries subject to sanctions or the threat of new or modified sanctions, more volatile and less liquid than U.S. investments. In addition, foreign markets can react differently to these conditions than the U.S. market.

Emerging Markets Risk

Emerging Markets Risk: Investments tied economically to emerging markets, especially frontier markets, can involve additional and greater risks than the risks associated with investments in developed markets. Emerging markets can have less developed markets, greater custody and operational risk, less developed legal, regulatory, and accounting systems, greater government involvement in the economy, greater risk of new or inconsistent government treatment of or restrictions on issuers and instruments, and greater political, social, geopolitical, and economic instability than developed markets.

Focus Risk

Focus Risk: Issuers in a single industry, sector, country, or region can react similarly to market, currency, political, economic, regulatory, geopolitical, environmental, public health, and other conditions, and the fund's performance will be affected by the conditions in the industries, sectors, countries, and regions to which the fund is exposed. Furthermore, investments in particular industries, sectors, countries, or regions may be more volatile than the broader market as a whole.

If MFS invests a significant percentage of the fund's assets in a single issuer or small number of issuers, the fund’s performance could be more volatile than the performance of more diversified funds.

Prepayment/Extension Risk

Prepayment/Extension Risk: Instruments subject to prepayment and/or extension can reduce the potential for gain for the instrument’s holders if the instrument is prepaid and increase the potential for loss if the maturity of the instrument is extended.

Municipal Risk

Municipal Risk: The price of a municipal instrument can be volatile and significantly affected by adverse tax changes or court rulings, legislative or political changes, changes in specific or general market and economic conditions and developments, and the financial condition of municipal issuers and insurers. Because many municipal instruments are issued to finance similar projects, conditions in certain industries can significantly affect the fund and the overall municipal market. Municipal instruments may be more susceptible to downgrades or defaults during economic downturns or similar periods of economic stress, which in turn could affect the market values and marketability of many or all municipal obligations of issuers in a state, U.S. territory, or possession.

In addition, because some municipal obligations may be secured or guaranteed by banks and other institutions, the risk associated with investments in such municipal securities could increase if the banking or financial sector suffers an economic downturn and/or if the credit ratings of the institutions issuing the guarantee are downgraded or at risk of being downgraded by a national rating organization. If such events occur, the value of the security could decrease or the value could be lost entirely, and it may be difficult or impossible to sell the security at the time and the price that normally prevails in the market.

When-Issued, Delayed Delivery, and Forward Commitment Transaction Risk

When-Issued, Delayed Delivery, and Forward Commitment Transaction Risk: The purchaser in a when-issued, delayed delivery or forward commitment transaction assumes the rights and risks of ownership, including the risks of price and yield fluctuations and the risk that the security will not be issued or delivered as anticipated. When-issued, delayed delivery, and forward commitment transactions can involve leverage. TBA transactions may significantly increase the fund's portfolio turnover rate.

Derivatives Risk

Derivatives Risk: Derivatives can be highly volatile and involve risks in addition to the risks of the underlying indicator(s) on which the derivative is based. Gains or losses from derivatives can be substantially greater than the derivatives’ original cost. Derivatives can involve leverage.

Leveraging Risk

Leveraging Risk: Leverage involves investment exposure in an amount exceeding the initial investment. Leverage can cause increased volatility by magnifying gains or losses.

Counterparty and Third Party Risk

Counterparty and Third Party Risk: Transactions involving a counterparty or third party other than the issuer of the instrument are subject to the credit risk of the counterparty or third party, and to the counterparty’s or third party’s ability or willingness to perform in accordance with the terms of the transaction.

Liquidity Risk

Liquidity Risk: It may be difficult to value, and it may not be possible to sell, certain investments, types of investments, and/or investments in certain segments of the market, and the fund may have to sell certain of these investments at prices or times that are not advantageous in order to meet redemptions or other cash needs.

Fluctuation of Net Asset Value and Share Price Risk

Fluctuation of Net Asset Value and Share Price Risk: The net asset value (NAV) per share of the fund will generally fluctuate with changes in the market value of the fund’s holdings. The fund’s shares can be bought and sold in the secondary market at market prices. Disruptions to purchases and sales, the existence of extreme market volatility, and/or a lack of an active trading market for the fund's shares may result in the fund's shares trading significantly above (at a premium) or below (at a discount) to NAV and bid/ask spreads may widen. Shares of the fund may trade at a larger premium or discount to the NAV than shares of other ETFs that focus on other market segments or types of securities. In addition, in stressed market conditions or periods of market disruption or volatility, the market for shares of the fund may become less liquid in response to deteriorating liquidity in the markets for the fund’s underlying portfolio holdings. If you buy fund shares when their market price is at a premium or sell fund shares when their market prices is at a discount, you may pay more than, or receive less than, NAV, respectively.

Authorized Participant Risks

Authorized Participant Risks: Only financial institutions authorized to transact daily with the fund (Authorized Participants) may engage in creation or redemption transactions directly with the fund, and Authorized Participants are not obligated to do so. To the extent an Authorized Participant cannot or is otherwise unwilling to engage in creation and redemption transactions, and no other Authorized Participant engages in such transactions, shares of the fund may trade at a significant discount or premium to NAV, experience wider intraday bid/ask spreads, and may face trading halts and/or delisting from the exchange.

Trading Issues Risk

Trading Issues Risk: There can be no assurance that an active trading market for the fund’s shares will develop or be maintained. In addition, trading of the fund’s shares may be halted or become less liquid. Shares of the fund, similar to shares of other issuers listed on a stock exchange, may be sold short and are therefore subject to the risk of increased volatility and price decreases associated with being sold short.

Most fund investors will buy and sell fund shares on the listing exchange or on another secondary market. When buying or selling shares of the fund, investors typically will pay brokerage commissions or other charges imposed by financial intermediaries as determined by that financial intermediary.

Cash Transactions Risk

Cash Transactions Risk: Unlike certain ETFs that distribute portfolio securities entirely in-kind, the fund may effect some or all creations and redemptions using cash, rather than in-kind securities. As a result, an investment in the fund may be less tax-efficient than an investment in an ETF that distributes portfolio securities entirely in-kind.

MFS Active Growth ETF
Risk Table - MFS Active Growth ETF
Risk [Text Block]
Principal Risks

Principal Risks

As with any exchange-traded fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.

The principal risks of investing in the fund are:

Risk Lose Money [Member] As with any exchange-traded fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund.
Risk Not Insured [Member] An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.
Investment Selection Risk

Investment Selection Risk: MFS' investment analysis and its selection of investments may not produce the intended results and/or can lead to an investment focus that results in the fund underperforming other funds with similar investment strategies and/or underperforming the markets in which the fund invests. In addition, to the extent MFS considers quantitative tools in managing the fund, such tools may not produce the intended results.

Equity Market Risk/Company Risk

Equity Market Risk/Company Risk: Equity markets are volatile and can decline significantly in response to changes in, or investor perceptions of, issuer, market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. These conditions can affect a single issuer or type of security, issuers within a broad market sector, industry or geographic region, or the equity markets in general. Certain events can have a dramatic adverse effect on equity markets and may lead to periods of high volatility in an equity market or a segment of an equity market. The value of an investment held by the fund may decline due to factors directly related to the issuer.

Growth Company Risk

Growth Company Risk: The stocks of growth companies can be more sensitive to the company’s earnings and more volatile than the market in general.

Foreign Risk

Foreign Risk: Exposure to foreign markets through issuers or currencies can involve additional risks relating to market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. These factors can make foreign investments, especially those tied economically to countries with developing economies or countries subject to sanctions or the threat of new or modified sanctions, more volatile and less liquid than U.S. investments. In addition, foreign markets can react differently to these conditions than the U.S. market.

Focus Risk

Focus Risk: Issuers in a single industry, sector, country, or region can react similarly to market, currency, political, economic, regulatory, geopolitical, environmental, public health, and other conditions, and the fund's performance will be affected by the conditions in the industries, sectors, countries, and regions to which the fund is exposed. Furthermore, investments in particular industries, sectors, countries, or regions may be more volatile than the broader market as a whole.

Non-Diversification Risk

Non-Diversification Risk: Because MFS may invest a significant percentage of the fund’s assets in a single issuer or small number of issuers, the fund’s performance could be closely tied to the value of that one issuer or issuers, and could be more volatile than the performance of diversified funds.

Liquidity Risk

Liquidity Risk: It may be difficult to value, and it may not be possible to sell, certain investments, types of investments, and/or investments in certain segments of the market, and the fund may have to sell certain of these investments at prices or times that are not advantageous in order to meet redemptions or other cash needs.

Fluctuation of Net Asset Value and Share Price Risk

Fluctuation of Net Asset Value and Share Price Risk: The net asset value (NAV) per share of the fund will generally fluctuate with changes in the market value of the fund’s holdings. The fund’s shares can be bought and sold in the secondary market at market prices. Disruptions to purchases and sales, the existence of extreme market volatility, and/or a lack of an active trading market for the fund's shares may result in the fund's shares trading significantly above (at a premium) or below (at a discount) to NAV and bid/ask spreads may widen. Shares of the fund may trade at a larger premium or discount to the NAV than shares of other ETFs that focus on other market segments or types of securities. In addition, in stressed market conditions or periods of market disruption or volatility, the market for shares of the fund may become less liquid in response to deteriorating liquidity in the markets for the fund’s underlying portfolio holdings. If you buy fund shares when their market price is at a premium or sell fund shares when their market prices is at a discount, you may pay more than, or receive less than, NAV, respectively.

Authorized Participant Risks

Authorized Participant Risks: Only financial institutions authorized to transact daily with the fund (Authorized Participants) may engage in creation or redemption transactions directly with the fund, and Authorized Participants are not obligated to do so. To the extent an Authorized Participant cannot or is otherwise unwilling to engage in creation and redemption transactions, and no other Authorized Participant engages in such transactions, shares of the fund may trade at a significant discount or premium to NAV, experience wider intraday bid/ask spreads, and may face trading halts and/or delisting from the exchange.

Trading Issues Risk

Trading Issues Risk: There can be no assurance that an active trading market for the fund’s shares will develop or be maintained. In addition, trading of the fund’s shares may be halted or become less liquid. Shares of the fund, similar to shares of other issuers listed on a stock exchange, may be sold short and are therefore subject to the risk of increased volatility and price decreases associated with being sold short.

Most fund investors will buy and sell fund shares on the listing exchange or on another secondary market. When buying or selling shares of the fund, investors typically will pay brokerage commissions or other charges imposed by financial intermediaries as determined by that financial intermediary.

Cash Transactions Risk

Cash Transactions Risk: Unlike certain ETFs that distribute portfolio securities entirely in-kind, the fund may effect some or all creations and redemptions using cash, rather than in-kind securities. As a result, an investment in the fund may be less tax-efficient than an investment in an ETF that distributes portfolio securities entirely in-kind.

MFS Active Intermediate Muni Bond ETF
Risk Table - MFS Active Intermediate Muni Bond ETF
Risk [Text Block]
Principal Risks

Principal Risks

As with any exchange-traded fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.

The principal risks of investing in the fund are:

Risk Lose Money [Member] As with any exchange-traded fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund.
Risk Not Insured [Member] An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.
Investment Selection Risk

Investment Selection Risk: MFS' investment analysis and its selection of investments may not produce the intended results and/or can lead to an investment focus that results in the fund underperforming other funds with similar investment strategies and/or underperforming the markets in which the fund invests. In addition, to the extent MFS considers quantitative tools in managing the fund, such tools may not produce the intended results.

Debt Market Risk

Debt Market Risk: Debt markets can be volatile and can decline significantly in response to changes in, or investor perceptions of, issuer, market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. These conditions can affect a single instrument, issuer, or borrower, a particular type of instrument, issuer, or borrower, a segment of the debt markets or the debt markets generally. Certain events can have a dramatic adverse effect on debt markets and may lead to periods of high volatility and reduced liquidity in a debt market or segment of a debt market.

Interest Rate Risk

Interest Rate Risk: In general, the price of a debt instrument falls when interest rates rise and rises when interest rates fall. Interest rate risk is generally greater for instruments with longer maturities or durations, or that do not pay current interest.

Credit Risk

Credit Risk: The price of a debt instrument depends, in part, on the credit quality of the issuer, borrower, counterparty, or other entity responsible for payment, or underlying collateral or assets and the terms of the instrument. The price of a debt instrument can decline in response to changes in, or perceptions of, the financial condition of the issuer, borrower, counterparty, or other entity, or underlying collateral or assets, or changes in, or perceptions of, specific or general market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. Debt instruments may be more susceptible to downgrades or defaults during economic downturns or similar periods of economic stress, which in turn could negatively affect the market value and liquidity of a debt instrument.

The credit quality of, and the ability to pay principal and interest when due by, an issuer of a municipal instrument depends on the credit quality of the entity supporting the municipal instrument, how essential any services supported by the municipal instrument are, the sufficiency of any revenues or taxes that support the municipal instrument, and/or the willingness or ability of the appropriate government entity to approve any appropriations necessary to support the municipal instrument. In addition, the price of a municipal instrument also depends on its credit quality and ability to meet the credit support obligations of any insurer or other entity providing credit support to a municipal instrument.

Below investment grade quality debt instruments (commonly referred to as “high yield securities” or “junk bonds”) can involve a

substantially greater risk of default or can already be in default, and their values can decline significantly. Below investment grade quality debt instruments are regarded as having predominantly speculative characteristics. Below investment grade quality debt instruments tend to be more sensitive to adverse news about the issuer, or the market or economy in general, than higher quality debt instruments.

Municipal Risk

Municipal Risk: The price of a municipal instrument can be volatile and significantly affected by adverse tax changes or court rulings, legislative or political changes, changes in specific or general market and economic conditions and developments, and the financial condition of municipal issuers and insurers. Because many municipal instruments are issued to finance similar projects, conditions in certain industries can significantly affect the fund and the overall municipal market. Municipal instruments may be more susceptible to downgrades or defaults during economic downturns or similar periods of economic stress, which in turn could affect the market values and marketability of many or all municipal obligations of issuers in a state, U.S. territory, or possession.

In addition, because some municipal obligations may be secured or guaranteed by banks and other institutions, the risk associated with investments in such municipal securities could increase if the banking or financial sector suffers an economic downturn and/or if the credit ratings of the institutions issuing the guarantee are downgraded or at risk of being downgraded by a national rating organization. If such events occur, the value of the security could decrease or the value could be lost entirely, and it may be difficult or impossible to sell the security at the time and the price that normally prevails in the market.

Focus Risk

Focus Risk: The fund’s performance will be closely tied to the issuer, market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions in the states, territories, and possessions of the United States in which the fund's assets are invested. If MFS invests a significant percentage of the fund's assets in a single state, territory, or possession, or a small number of states, territories, or possessions, these conditions will have a significant impact on the fund's performance and the fund's performance may be more volatile than the performance of more geographically-diversified funds.

Prepayment/Extension Risk

Prepayment/Extension Risk: Instruments subject to prepayment and/or extension can reduce the potential for gain for the instrument’s holders if the instrument is prepaid and increase the potential for loss if the maturity of the instrument is extended.

Derivatives Risk

Derivatives Risk: Derivatives can be highly volatile and involve risks in addition to the risks of the underlying indicator(s) on which the derivative is based. Gains or losses from derivatives can be substantially greater than the derivatives’ original cost. Derivatives can involve leverage.

Leveraging Risk

Leveraging Risk: Leverage involves investment exposure in an amount exceeding the initial investment. Leverage can cause increased volatility by magnifying gains or losses.

Counterparty and Third Party Risk

Counterparty and Third Party Risk: Transactions involving a counterparty or third party other than the issuer of the instrument are subject to the credit risk of the counterparty or third party, and to the counterparty’s or third party’s ability or willingness to perform in accordance with the terms of the transaction.

Liquidity Risk

Liquidity Risk: It may be difficult to value, and it may not be possible to sell, certain investments, types of investments, and/or investments in certain segments of the market, and the fund may have to sell certain of these investments at prices or times that are not advantageous in order to meet redemptions or other cash needs.

Fluctuation of Net Asset Value and Share Price Risk

Fluctuation of Net Asset Value and Share Price Risk: The net asset value (NAV) per share of the fund will generally fluctuate with changes in the market value of the fund’s holdings. The fund’s shares can be bought and sold in the secondary market at market prices. Disruptions to purchases and sales, the existence of extreme market volatility, and/or a lack of an active trading market for the fund's shares may result in the fund's shares trading significantly above (at a premium) or below (at a discount) to NAV and bid/ask spreads may widen. Shares of the fund may trade at a larger premium or discount to the NAV than shares of other ETFs that focus on other market segments or types of securities. In addition, in stressed market conditions or periods of market disruption or volatility, the market for shares of the fund may become less liquid in response to deteriorating liquidity in the markets for the fund’s underlying portfolio holdings. If you buy fund shares when their market price is at a premium or sell fund shares when their market prices is at a discount, you may pay more than, or receive less than, NAV, respectively.

Authorized Participant Risks

Authorized Participant Risks: Only financial institutions authorized to transact daily with the fund (Authorized Participants) may engage in creation or redemption transactions directly with the fund, and Authorized Participants are not obligated to do so. To the extent an Authorized Participant cannot or is otherwise unwilling to engage in creation and redemption transactions, and no other Authorized Participant engages in such transactions, shares of the fund may trade at a significant discount or premium to NAV, experience wider intraday bid/ask spreads, and may face trading halts and/or delisting from the exchange.

Trading Issues Risk

Trading Issues Risk: There can be no assurance that an active trading market for the fund’s shares will develop or be maintained. In addition, trading of the fund’s shares may be halted or become less liquid. Shares of the fund, similar to shares of other issuers listed on a stock exchange, may be sold short and are therefore subject to the risk of increased volatility and price decreases associated with being sold short.

Most fund investors will buy and sell fund shares on the listing exchange or on another secondary market. When buying or selling shares of the fund, investors typically will pay brokerage commissions or other charges imposed by financial intermediaries as determined by that financial intermediary.

Cash Transactions Risk

Cash Transactions Risk: Unlike certain ETFs that distribute portfolio securities entirely in-kind, the fund may effect some or all creations and redemptions using cash, rather than in-kind securities. As a result, an investment in the fund may be less tax-efficient than an investment in an ETF that distributes portfolio securities entirely in-kind.

MFS Active International ETF
Risk Table - MFS Active International ETF
Risk [Text Block]
Principal Risks

Principal Risks

As with any exchange-traded fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.

The principal risks of investing in the fund are:

Risk Lose Money [Member] As with any exchange-traded fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund.
Risk Not Insured [Member] An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.
Investment Selection Risk

Investment Selection Risk: MFS' investment analysis, its development and use of quantitative models, and its selection of investments may not produce the intended results and/or can lead to an investment focus that results in the fund underperforming other funds with similar investment strategies and/or underperforming the markets in which the fund invests. The quantitative models used by MFS (both proprietary and third-party) may not produce the intended results for a variety of reasons, including the factors used in the models, the weight placed on each factor in the models, changes from the market factors' historical trends, changing sources of market return or market risk, and technical issues in the design, development, implementation, application, and maintenance of the models (e.g., incomplete, stale, or inaccurate data, human error, programming or other software issues, coding errors, and technology failures).

Equity Market Risk/Company Risk

Equity Market Risk/Company Risk: Equity markets are volatile and can decline significantly in response to changes in, or investor perceptions of, issuer, market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. These conditions can affect a single issuer or type of security, issuers within a broad market sector, industry or geographic region, or the equity markets in general. Certain events can have a dramatic adverse effect on equity markets and may lead to periods of high volatility in an equity market or a segment of an equity market. The value of an investment held by the fund may decline due to factors directly related to the issuer.

Growth Company Risk

Growth Company Risk: The stocks of growth companies can be more sensitive to the company’s earnings and more volatile than the market in general.

Value Company Risk

Value Company Risk: The stocks of value companies can continue to be undervalued for long periods of time and not realize their expected value and can be more volatile than the market in general.

Foreign Risk

Foreign Risk: Exposure to foreign markets through issuers or currencies can involve additional risks relating to market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. These factors can make foreign investments, especially those tied economically to emerging markets or countries subject to sanctions or the threat of new or modified sanctions, more volatile and less liquid than U.S. investments. In addition, foreign markets can react differently to these conditions than the U.S. market.

Emerging Markets Risk

Emerging Markets Risk: Investments tied economically to emerging markets, especially frontier markets, can involve additional and greater risks than the risks associated with investments in developed markets. Emerging markets can have less developed markets, greater custody and operational risk, less developed legal, regulatory, and accounting systems, greater government involvement in the economy, greater risk of new or inconsistent government treatment of or restrictions on issuers and instruments, and greater political, social, geopolitical, and economic instability than developed markets.

Currency Risk

Currency Risk: The value of foreign currencies relative to the U.S. dollar fluctuates in response to market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions, and changes in currency exchange rates impact the

financial condition of companies or other issuers and may change the value in U.S. dollars of investments denominated in foreign currencies.

Focus Risk

Focus Risk: Issuers in a single industry, sector, country, or region can react similarly to market, currency, political, economic, regulatory, geopolitical, environmental, public health, and other conditions, and the fund's performance will be affected by the conditions in the industries, sectors, countries, and regions to which the fund is exposed. Furthermore, investments in particular industries, sectors, countries, or regions may be more volatile than the broader market as a whole.

Liquidity Risk

Liquidity Risk: It may be difficult to value, and it may not be possible to sell, certain investments, types of investments, and/or investments in certain segments of the market, and the fund may have to sell certain of these investments at prices or times that are not advantageous in order to meet redemptions or other cash needs.

Fluctuation of Net Asset Value and Share Price Risk

Fluctuation of Net Asset Value and Share Price Risk: The net asset value (NAV) per share of the fund will generally fluctuate with changes in the market value of the fund’s holdings. The fund’s shares can be bought and sold in the secondary market at market prices. Disruptions to purchases and sales, the existence of extreme market volatility, and/or a lack of an active trading market for the fund's shares may result in the fund's shares trading significantly above (at a premium) or below (at a discount) to NAV and bid/ask spreads may widen. Shares of the fund may trade at a larger premium or discount to the NAV than shares of other ETFs that focus on other market segments or types of securities. In addition, in stressed market conditions or periods of market disruption or volatility, the market for shares of the fund may become less liquid in response to deteriorating liquidity in the markets for the fund’s underlying portfolio holdings. If you buy fund shares when their market price is at a premium or sell fund shares when their market prices is at a discount, you may pay more than, or receive less than, NAV, respectively.

Authorized Participant Risks

Authorized Participant Risks: Only financial institutions authorized to transact daily with the fund (Authorized Participants) may engage in creation or redemption transactions directly with the fund, and Authorized Participants are not obligated to do so. To the extent an Authorized Participant cannot or is otherwise unwilling to engage in creation and redemption transactions, and no other Authorized Participant engages in such transactions, shares of the fund may trade at a significant discount or premium to NAV, experience wider intraday bid/ask spreads, and may face trading halts and/or delisting from the exchange.

Trading Issues Risk

Trading Issues Risk: There can be no assurance that an active trading market for the fund’s shares will develop or be maintained. In addition, trading of the fund’s shares may be halted or become less liquid. Shares of the fund, similar to shares of other issuers listed on a stock exchange, may be sold short and are therefore subject to the risk of increased volatility and price decreases associated with being sold short.

Most fund investors will buy and sell fund shares on the listing exchange or on another secondary market. When buying or selling shares of the fund, investors typically will pay brokerage commissions or other charges imposed by financial intermediaries as determined by that financial intermediary.

Cash Transactions Risk

Cash Transactions Risk: Unlike certain ETFs that distribute portfolio securities entirely in-kind, the fund may effect some or all creations and redemptions using cash, rather than in-kind securities. As a result, an investment in the fund may be less tax-efficient than an investment in an ETF that distributes portfolio securities entirely in-kind.

MFS Active Mid Cap ETF
Risk Table - MFS Active Mid Cap ETF
Risk [Text Block]
Principal Risks

Principal Risks

As with any exchange-traded fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.

The principal risks of investing in the fund are:

Risk Lose Money [Member] As with any exchange-traded fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund.
Risk Not Insured [Member] An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.
Investment Selection Risk

Investment Selection Risk: MFS' investment analysis and its selection of investments may not produce the intended results and/or can lead to an investment focus that results in the fund underperforming other funds with similar investment strategies and/or underperforming the markets in which the fund invests. In addition, to the extent MFS considers quantitative tools in managing the fund, such tools may not produce the intended results.

Equity Market Risk/Company Risk

Equity Market Risk/Company Risk: Equity markets are volatile and can decline significantly in response to changes in, or investor perceptions of, issuer, market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. These conditions can affect a single issuer or type of security, issuers within a broad market sector, industry or geographic region, or the equity markets in general. Certain events can have a dramatic adverse effect on equity markets and may lead to periods of high volatility in an equity market or a segment of an equity market. The value of an investment held by the fund may decline due to factors directly related to the issuer.

Growth Company Risk

Growth Company Risk: The stocks of growth companies can be more sensitive to the company’s earnings and more volatile than the market in general.

Value Company Risk

Value Company Risk: The stocks of value companies can continue to be undervalued for long periods of time and not realize their expected value and can be more volatile than the market in general.

Mid Cap Risk

Mid Cap Risk: The stocks of mid cap companies can be more volatile and their shares can be less liquid than those of larger companies.

Foreign Risk

Foreign Risk: Exposure to foreign markets through issuers or currencies can involve additional risks relating to market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. These factors can make foreign investments, especially those tied economically to countries with developing economies or countries subject to sanctions or the threat of new or modified sanctions, more volatile and less liquid than U.S. investments. In addition, foreign markets can react differently to these conditions than the U.S. market.

Focus Risk

Focus Risk: Issuers in a single industry, sector, country, or region can react similarly to market, currency, political, economic, regulatory, geopolitical, environmental, public health, and other conditions, and the fund's performance will be affected by the conditions in the industries, sectors, countries, and regions to which the fund is exposed. Furthermore, investments in particular industries, sectors, countries, or regions may be more volatile than the broader market as a whole.

Leveraging Risk

Leveraging Risk: Leverage involves investment exposure in an amount exceeding the initial investment. Leverage can cause increased volatility by magnifying gains or losses.

Liquidity Risk

Liquidity Risk: It may be difficult to value, and it may not be possible to sell, certain investments, types of investments, and/or investments in certain segments of the market, and the fund may have to sell certain of these investments at prices or times that are not advantageous in order to meet redemptions or other cash needs.

Capacity Risk

Capacity Risk: The markets and securities in which the fund primarily invests may, at times, have limited capacity, and as an ETF, the fund cannot be closed to new investors as a means of managing capacity. During periods of capacity constraints, the implementation and execution of the fund’s strategy, including the portfolio securities purchased, held, and sold by the fund, may change, and capacity limitations may negatively impact the performance of the fund.

Fluctuation of Net Asset Value and Share Price Risk

Fluctuation of Net Asset Value and Share Price Risk: The net asset value (NAV) per share of the fund will generally fluctuate with changes in the market value of the fund’s holdings. The fund’s shares can be bought and sold in the secondary market at market prices. Disruptions to purchases and sales, the existence of extreme market volatility, and/or a lack of an active trading market for the fund's shares may result in the fund's shares trading significantly above (at a premium) or below (at a discount) to NAV and bid/ask spreads may widen. Shares of the fund may trade at a larger premium or discount to the NAV than shares of other ETFs that focus on other market segments or types of securities. In addition, in stressed market conditions or periods of market disruption or volatility, the market for shares of the fund may become less liquid in response to deteriorating liquidity in the markets for the fund’s underlying portfolio holdings. If you buy fund shares when their market price is at a premium or sell fund shares when their market prices is at a discount, you may pay more than, or receive less than, NAV, respectively.

Authorized Participant Risks

Authorized Participant Risks: Only financial institutions authorized to transact daily with the fund (Authorized Participants) may engage in creation or redemption transactions directly with the fund, and Authorized Participants are not obligated to do so. To the extent an Authorized Participant cannot or is otherwise unwilling to engage in creation and redemption transactions, and no other Authorized Participant engages in such transactions, shares of the fund may trade at a significant discount or premium to NAV, experience wider intraday bid/ask spreads, and may face trading halts and/or delisting from the exchange.

Trading Issues Risk

Trading Issues Risk: There can be no assurance that an active trading market for the fund’s shares will develop or be maintained. In addition, trading of the fund’s shares may be halted or become less liquid. Shares of the fund, similar to shares of other issuers listed on a stock exchange, may be sold short and are therefore subject to the risk of increased volatility and price decreases associated with being sold short.

Most fund investors will buy and sell fund shares on the listing exchange or on another secondary market. When buying or selling shares of the fund, investors typically will pay brokerage commissions or other charges imposed by financial intermediaries as determined by that financial intermediary.

Cash Transactions Risk

Cash Transactions Risk: Unlike certain ETFs that distribute portfolio securities entirely in-kind, the fund may effect some or all creations and redemptions using cash, rather than in-kind securities. As a result, an investment in the fund may be less tax-efficient than an investment in an ETF that distributes portfolio securities entirely in-kind.

MFS Active Value ETF
Risk Table - MFS Active Value ETF
Risk [Text Block]
Principal Risks

Principal Risks

As with any exchange-traded fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.

The principal risks of investing in the fund are:

Risk Lose Money [Member] As with any exchange-traded fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund.
Risk Not Insured [Member] An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.
Investment Selection Risk

Investment Selection Risk: MFS' investment analysis and its selection of investments may not produce the intended results and/or can lead to an investment focus that results in the fund underperforming other funds with similar investment strategies and/or underperforming the markets in which the fund invests. In addition, to the extent MFS considers quantitative tools in managing the fund, such tools may not produce the intended results.

Equity Market Risk/Company Risk

Equity Market Risk/Company Risk: Equity markets are volatile and can decline significantly in response to changes in, or investor perceptions of, issuer, market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. These conditions can affect a single issuer or type of security, issuers within a broad market sector, industry or geographic region, or the equity markets in general. Certain events can have a dramatic adverse effect on equity markets and may lead to periods of high volatility in an equity market or a segment of an equity market. The value of an investment held by the fund may decline due to factors directly related to the issuer.

Value Company Risk

Value Company Risk: The stocks of value companies can continue to be undervalued for long periods of time and not realize their expected value and can be more volatile than the market in general.

Foreign Risk

Foreign Risk: Exposure to foreign markets through issuers or currencies can involve additional risks relating to market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. These factors can make foreign investments, especially those tied economically to countries with developing economies or countries subject to sanctions or the threat of new or modified sanctions, more volatile and less liquid than U.S. investments. In addition, foreign markets can react differently to these conditions than the U.S. market.

Focus Risk

Focus Risk: Issuers in a single industry, sector, country, or region can react similarly to market, currency, political, economic, regulatory, geopolitical, environmental, public health, and other conditions, and the fund's performance will be affected by the conditions in the industries, sectors, countries, and regions to which the fund is exposed. Furthermore, investments in particular industries, sectors, countries, or regions may be more volatile than the broader market as a whole.

Liquidity Risk

Liquidity Risk: It may be difficult to value, and it may not be possible to sell, certain investments, types of investments, and/or investments in certain segments of the market, and the fund may have to sell certain of these investments at prices or times that are not advantageous in order to meet redemptions or other cash needs.

Fluctuation of Net Asset Value and Share Price Risk

Fluctuation of Net Asset Value and Share Price Risk: The net asset value (NAV) per share of the fund will generally fluctuate with changes in the market value of the fund’s holdings. The fund’s shares can be bought and sold in the secondary market at market prices. Disruptions to purchases and sales, the existence of extreme market volatility, and/or a lack of an active trading market for the

fund's shares may result in the fund's shares trading significantly above (at a premium) or below (at a discount) to NAV and bid/ask spreads may widen. Shares of the fund may trade at a larger premium or discount to the NAV than shares of other ETFs that focus on other market segments or types of securities. In addition, in stressed market conditions or periods of market disruption or volatility, the market for shares of the fund may become less liquid in response to deteriorating liquidity in the markets for the fund’s underlying portfolio holdings. If you buy fund shares when their market price is at a premium or sell fund shares when their market prices is at a discount, you may pay more than, or receive less than, NAV, respectively.

Authorized Participant Risks

Authorized Participant Risks: Only financial institutions authorized to transact daily with the fund (Authorized Participants) may engage in creation or redemption transactions directly with the fund, and Authorized Participants are not obligated to do so. To the extent an Authorized Participant cannot or is otherwise unwilling to engage in creation and redemption transactions, and no other Authorized Participant engages in such transactions, shares of the fund may trade at a significant discount or premium to NAV, experience wider intraday bid/ask spreads, and may face trading halts and/or delisting from the exchange.

Trading Issues Risk

Trading Issues Risk: There can be no assurance that an active trading market for the fund’s shares will develop or be maintained. In addition, trading of the fund’s shares may be halted or become less liquid. Shares of the fund, similar to shares of other issuers listed on a stock exchange, may be sold short and are therefore subject to the risk of increased volatility and price decreases associated with being sold short.

Most fund investors will buy and sell fund shares on the listing exchange or on another secondary market. When buying or selling shares of the fund, investors typically will pay brokerage commissions or other charges imposed by financial intermediaries as determined by that financial intermediary.

Cash Transactions Risk

Cash Transactions Risk: Unlike certain ETFs that distribute portfolio securities entirely in-kind, the fund may effect some or all creations and redemptions using cash, rather than in-kind securities. As a result, an investment in the fund may be less tax-efficient than an investment in an ETF that distributes portfolio securities entirely in-kind.

MFS Blended Research Core Equity ETF
Risk Table - MFS Blended Research Core Equity ETF
Risk [Text Block]
Principal Risks

Principal Risks

As with any exchange-traded fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.

The principal risks of investing in the fund are:

Risk Lose Money [Member] As with any exchange-traded fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund.
Risk Not Insured [Member] An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.
Investment Selection Risk

Investment Selection Risk: MFS' investment analysis, its development and use of quantitative models, and its selection of investments may not produce the intended results and/or can lead to an investment focus that results in the fund underperforming other funds with similar investment strategies and/or underperforming the markets in which the fund invests. The quantitative models used by MFS (both proprietary and third-party) may not produce the intended results for a variety of reasons, including the factors used in the models, the weight placed on each factor in the models, changes from the market factors' historical trends, changing sources of market return or market risk, and technical issues in the design, development, implementation, application, and maintenance of the models (e.g., incomplete, stale, or inaccurate data, human error, programming or other software issues, coding errors, and technology failures).

Equity Market Risk/Company Risk

Equity Market Risk/Company Risk: Equity markets are volatile and can decline significantly in response to changes in, or investor perceptions of, issuer, market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. These conditions can affect a single issuer or type of security, issuers within a broad market sector, industry or geographic region, or the equity markets in general. Certain events can have a dramatic adverse effect on equity markets and may lead to periods of high volatility in an equity market or a segment of an equity market. The value of an investment held by the fund may decline due to factors directly related to the issuer.

Growth Company Risk

Growth Company Risk: The stocks of growth companies can be more sensitive to the company’s earnings and more volatile than the market in general.

Value Company Risk

Value Company Risk: The stocks of value companies can continue to be undervalued for long periods of time and not realize

their expected value and can be more volatile than the market in general.

Investment Strategy Risk

Investment Strategy Risk: There is no assurance that the fund's predicted tracking error will equal its target predicted tracking error at any point in time or consistently for any period of time, or that the fund's predicted tracking error and actual tracking error will be similar. The fund's strategy to target a predicted tracking error of approximately 2% compared to the Standard & Poor's 500 Stock Index and to blend fundamental and quantitative research may not produce the intended results. In addition, MFS' fundamental research is not available for all issuers.

Foreign Risk

Foreign Risk: Exposure to foreign markets through issuers or currencies can involve additional risks relating to market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. These factors can make foreign investments, especially those tied economically to countries with developing economies or countries subject to sanctions or the threat of new or modified sanctions, more volatile and less liquid than U.S. investments. In addition, foreign markets can react differently to these conditions than the U.S. market.

Focus Risk

Focus Risk: Issuers in a single industry, sector, country, or region can react similarly to market, currency, political, economic, regulatory, geopolitical, environmental, public health, and other conditions, and the fund's performance will be affected by the conditions in the industries, sectors, countries, and regions to which the fund is exposed. Furthermore, investments in particular industries, sectors, countries, or regions may be more volatile than the broader market as a whole.

If MFS invests a significant percentage of the fund's assets in a single issuer or small number of issuers, the fund’s performance could be more volatile than the performance of more diversified funds.

Liquidity Risk

Liquidity Risk: It may be difficult to value, and it may not be possible to sell, certain investments, types of investments, and/or investments in certain segments of the market, and the fund may have to sell certain of these investments at prices or times that are not advantageous in order to meet redemptions or other cash needs.

Fluctuation of Net Asset Value and Share Price Risk

Fluctuation of Net Asset Value and Share Price Risk: The net asset value (NAV) per share of the fund will generally fluctuate with changes in the market value of the fund’s holdings. The fund’s shares can be bought and sold in the secondary market at market prices. Disruptions to purchases and sales, the existence of extreme market volatility, and/or a lack of an active trading market for the fund's shares may result in the fund's shares trading significantly above (at a premium) or below (at a discount) to NAV and bid/ask spreads may widen. Shares of the fund may trade at a larger premium or discount to the NAV than shares of other ETFs that focus on other market segments or types of securities. In addition, in stressed market conditions or periods of market disruption or volatility, the market for shares of the fund may become less liquid in response to deteriorating liquidity in the markets for the fund’s underlying portfolio holdings. If you buy fund shares when their market price is at a premium or sell fund shares when their market prices is at a discount, you may pay more than, or receive less than, NAV, respectively.

Authorized Participant Risks

Authorized Participant Risks: Only financial institutions authorized to transact daily with the fund (Authorized Participants) may engage in creation or redemption transactions directly with the fund, and Authorized Participants are not obligated to do so. To the extent an Authorized Participant cannot or is otherwise unwilling to engage in creation and redemption transactions, and no other Authorized Participant engages in such transactions, shares of the fund may trade at a significant discount or premium to NAV, experience wider intraday bid/ask spreads, and may face trading halts and/or delisting from the exchange.

Trading Issues Risk

Trading Issues Risk: There can be no assurance that an active trading market for the fund’s shares will develop or be maintained. In addition, trading of the fund’s shares may be halted or become less liquid. Shares of the fund, similar to shares of other issuers listed on a stock exchange, may be sold short and are therefore subject to the risk of increased volatility and price decreases associated with being sold short.

Most fund investors will buy and sell fund shares on the listing exchange or on another secondary market. When buying or selling shares of the fund, investors typically will pay brokerage commissions or other charges imposed by financial intermediaries as determined by that financial intermediary.

Cash Transactions Risk

Cash Transactions Risk: Unlike certain ETFs that distribute portfolio securities entirely in-kind, the fund may effect some or all creations and redemptions using cash, rather than in-kind securities. As a result, an investment in the fund may be less tax-efficient than an investment in an ETF that distributes portfolio securities entirely in-kind.

MFS Blended Research Emerging Markets Equity ETF
Risk Table - MFS Blended Research Emerging Markets Equity ETF
Risk [Text Block]
Principal Risks

Principal Risks

As with any exchange-traded fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.

The principal risks of investing in the fund are:

Risk Lose Money [Member] As with any exchange-traded fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund.
Risk Not Insured [Member] An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.
Investment Selection Risk

Investment Selection Risk: MFS' investment analysis, its development and use of quantitative models, and its selection of investments may not produce the intended results and/or can lead to an investment focus that results in the fund underperforming other funds with similar investment strategies and/or underperforming the markets in which the fund invests. The quantitative models used by MFS (both proprietary and third-party) may not produce the intended results for a variety of reasons, including the factors used in the models, the weight placed on each factor in the models, changes from the market factors' historical trends, changing sources of market return or market risk, and technical issues in the design, development, implementation, application, and maintenance of the models (e.g., incomplete, stale, or inaccurate data, human error, programming or other software issues, coding errors, and technology failures).

Equity Market Risk/Company Risk

Equity Market Risk/Company Risk: Equity markets are volatile and can decline significantly in response to changes in, or investor perceptions of, issuer, market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. These conditions can affect a single issuer or type of security, issuers within a broad market sector, industry or geographic region, or the equity markets in general. Certain events can have a dramatic adverse effect on equity markets and may lead to periods of high volatility in an equity market or a segment of an equity market. The value of an investment held by the fund may decline due to factors directly related to the issuer.

Investment Strategy Risk

Investment Strategy Risk: There is no assurance that the fund's predicted tracking error will equal its target predicted tracking error at any point in time or consistently for any period of time, or that the fund's predicted tracking error and actual tracking error will be similar. The fund's strategy to target a predicted tracking error of

approximately 2% compared to the MSCI Emerging Markets Index and to blend fundamental and quantitative research may not produce the intended results. In addition, MFS' fundamental research is not available for all issuers.

Foreign Risk

Foreign Risk: Exposure to foreign markets through issuers or currencies can involve additional risks relating to market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. These factors can make foreign investments, especially those tied economically to emerging markets or countries subject to sanctions or the threat of new or modified sanctions, more volatile and less liquid than U.S. investments. In addition, foreign markets can react differently to these conditions than the U.S. market.

Emerging Markets Risk

Emerging Markets Risk: Investments tied economically to emerging markets, especially frontier markets, can involve additional and greater risks than the risks associated with investments in developed markets. Emerging markets can have less developed markets, greater custody and operational risk, less developed legal, regulatory, and accounting systems, greater government involvement in the economy, greater risk of new or inconsistent government treatment of or restrictions on issuers and instruments, and greater political, social, geopolitical, and economic instability than developed markets.

Currency Risk

Currency Risk: The value of foreign currencies relative to the U.S. dollar fluctuates in response to market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions, and changes in currency exchange rates impact the financial condition of companies or other issuers and may change the value in U.S. dollars of investments denominated in foreign currencies.

Focus Risk

Focus Risk: Issuers in a single industry, sector, country, or region can react similarly to market, currency, political, economic, regulatory, geopolitical, environmental, public health, and other conditions, and the fund's performance will be affected by the conditions in the industries, sectors, countries, and regions to which the fund is exposed. Furthermore, investments in particular industries, sectors, countries, or regions may be more volatile than the broader market as a whole.

Liquidity Risk

Liquidity Risk: It may be difficult to value, and it may not be possible to sell, certain investments, types of investments, and/or investments in certain segments of the market, and the fund may have to sell certain of these investments at prices or times that are not advantageous in order to meet redemptions or other cash needs.

Capacity Risk

Capacity Risk: The markets and securities in which the fund primarily invests may, at times, have limited capacity, and as an ETF, the fund cannot be closed to new investors as a means of managing capacity. During periods of capacity constraints, the implementation and execution of the fund’s strategy, including the portfolio securities purchased, held, and sold by the fund, may change, and capacity limitations may negatively impact the performance of the fund.

Fluctuation of Net Asset Value and Share Price Risk

Fluctuation of Net Asset Value and Share Price Risk: The net asset value (NAV) per share of the fund will generally fluctuate with changes in the market value of the fund’s holdings. The fund’s shares can be bought and sold in the secondary market at market prices. Disruptions to purchases and sales, the existence of extreme market volatility, and/or a lack of an active trading market for the fund's shares may result in the fund's shares trading significantly above (at a premium) or below (at a discount) to NAV and bid/ask spreads may widen. Shares of the fund may trade at a larger premium or discount to the NAV than shares of other ETFs that focus on other market segments or types of securities. In addition, in stressed market conditions or periods of market disruption or volatility, the market for shares of the fund may become less liquid in response to deteriorating liquidity in the markets for the fund’s underlying portfolio holdings. If you buy fund shares when their market price is at a premium or sell fund shares when their market prices is at a discount, you may pay more than, or receive less than, NAV, respectively.

Authorized Participant Risks

Authorized Participant Risks: Only financial institutions authorized to transact daily with the fund (Authorized Participants) may engage in creation or redemption transactions directly with the fund, and Authorized Participants are not obligated to do so. To the extent an Authorized Participant cannot or is otherwise unwilling to engage in creation and redemption transactions, and no other Authorized Participant engages in such transactions, shares of the fund may trade at a significant discount or premium to NAV, experience wider intraday bid/ask spreads, and may face trading halts and/or delisting from the exchange.

Trading Issues Risk

Trading Issues Risk: There can be no assurance that an active trading market for the fund’s shares will develop or be maintained. In addition, trading of the fund’s shares may be halted or become less liquid. Shares of the fund, similar to shares of other issuers listed on a stock exchange, may be sold short and are therefore subject to the risk of increased volatility and price decreases associated with being sold short.

Most fund investors will buy and sell fund shares on the listing exchange or on another secondary market. When buying or selling shares of the fund, investors typically will pay brokerage commissions or other charges imposed by financial intermediaries as determined by that financial intermediary.

Cash Transactions Risk

Cash Transactions Risk: Unlike certain ETFs that distribute portfolio securities entirely in-kind, the fund may effect some or all creations and redemptions using cash, rather than in-kind securities. As a result, an investment in the fund may be less tax-efficient than an investment in an ETF that distributes portfolio securities entirely in-kind.

MFS Blended Research International Equity ETF
Risk Table - MFS Blended Research International Equity ETF
Risk [Text Block]
Principal Risks

Principal Risks

As with any exchange-traded fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.

The principal risks of investing in the fund are:

Risk Lose Money [Member] As with any exchange-traded fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund.
Risk Not Insured [Member] An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.
Investment Selection Risk

Investment Selection Risk: MFS' investment analysis, its development and use of quantitative models, and its selection of investments may not produce the intended results and/or can lead to an investment focus that results in the fund underperforming other funds with similar investment strategies and/or underperforming the markets in which the fund invests. The quantitative models used by MFS (both proprietary and third-party) may not produce the intended results for a variety of reasons, including the factors used in the models, the weight placed on each factor in the models, changes from the market factors' historical trends, changing sources of market return or market risk, and technical issues in the design, development, implementation, application, and maintenance of the models (e.g., incomplete, stale, or inaccurate data, human error, programming or other software issues, coding errors, and technology failures).

Equity Market Risk/Company Risk

Equity Market Risk/Company Risk: Equity markets are volatile and can decline significantly in response to changes in, or investor perceptions of, issuer, market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. These conditions can affect a single issuer or type of security, issuers within a broad market sector, industry or geographic region, or the equity markets in general. Certain events can have a dramatic adverse effect on equity markets and may lead to periods of high volatility in an equity market or a segment of an equity market. The value of an investment held by the fund may decline due to factors directly related to the issuer.

Growth Company Risk

Growth Company Risk: The stocks of growth companies can be more sensitive to the company’s earnings and more volatile than the market in general.

Value Company Risk

Value Company Risk: The stocks of value companies can continue to be undervalued for long periods of time and not realize their expected value and can be more volatile than the market in general.

Investment Strategy Risk

Investment Strategy Risk: There is no assurance that the fund's predicted tracking error will equal its target predicted tracking error at any point in time or consistently for any period of time, or that the fund's predicted tracking error and actual tracking error will be similar. The fund's strategy to target a predicted tracking error of approximately 2% compared to the MSCI All Country World (ex-US) Index and to blend fundamental and quantitative research may not produce the intended results. In addition, MFS' fundamental research is not available for all issuers.

Foreign Risk

Foreign Risk: Exposure to foreign markets through issuers or currencies can involve additional risks relating to market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. These factors can make foreign investments, especially those tied economically to emerging markets or countries subject to sanctions or the threat of new or modified sanctions, more volatile and less liquid than U.S. investments. In addition, foreign markets can react differently to these conditions than the U.S. market.

Emerging Markets Risk

Emerging Markets Risk: Investments tied economically to emerging markets, especially frontier markets, can involve additional and greater risks than the risks associated with investments in developed markets. Emerging markets can have less developed markets, greater custody and operational risk, less developed legal, regulatory, and accounting systems, greater government involvement in the economy, greater risk of new or inconsistent government treatment of or restrictions on issuers and instruments, and greater political, social, geopolitical, and economic instability than developed markets.

Currency Risk

Currency Risk: The value of foreign currencies relative to the U.S. dollar fluctuates in response to market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions, and changes in currency exchange rates impact the financial condition of companies or other issuers and may change the value in U.S. dollars of investments denominated in foreign currencies.

Focus Risk

Focus Risk: Issuers in a single industry, sector, country, or region can react similarly to market, currency, political, economic, regulatory, geopolitical, environmental, public health, and other conditions, and the fund's performance will be affected by the conditions in the industries, sectors, countries, and regions to which the fund is exposed. Furthermore, investments in particular industries, sectors, countries, or regions may be more volatile than the broader market as a whole.

Liquidity Risk

Liquidity Risk: It may be difficult to value, and it may not be possible to sell, certain investments, types of investments, and/or investments in certain segments of the market, and the fund may have to sell certain of these investments at prices or times that are not advantageous in order to meet redemptions or other cash needs.

Fluctuation of Net Asset Value and Share Price Risk

Fluctuation of Net Asset Value and Share Price Risk: The net asset value (NAV) per share of the fund will generally fluctuate with changes in the market value of the fund’s holdings. The fund’s shares can be bought and sold in the secondary market at market prices. Disruptions to purchases and sales, the existence of extreme market volatility, and/or a lack of an active trading market for the fund's shares may result in the fund's shares trading significantly above (at a premium) or below (at a discount) to NAV and bid/ask spreads may widen. Shares of the fund may trade at a larger premium or discount to the NAV than shares of other ETFs that focus on other market segments or types of securities. In addition, in stressed market conditions or periods of market disruption or volatility, the market for shares of the fund may become less liquid in response to deteriorating liquidity in the markets for the fund’s underlying portfolio holdings. If you buy fund shares when their market price is at a premium or sell fund shares when their market prices is at a discount, you may pay more than, or receive less than, NAV, respectively.

Authorized Participant Risks

Authorized Participant Risks: Only financial institutions authorized to transact daily with the fund (Authorized Participants) may engage in creation or redemption transactions directly with the fund, and Authorized Participants are not obligated to do so. To the extent an Authorized Participant cannot or is otherwise unwilling to engage in creation and redemption transactions, and no other Authorized Participant engages in such transactions, shares of the fund may trade at a significant discount or premium to NAV, experience wider intraday bid/ask spreads, and may face trading halts and/or delisting from the exchange.

Trading Issues Risk

Trading Issues Risk: There can be no assurance that an active trading market for the fund’s shares will develop or be maintained. In addition, trading of the fund’s shares may be halted or become less liquid. Shares of the fund, similar to shares of other issuers listed on a stock exchange, may be sold short and are therefore subject to the risk of increased volatility and price decreases associated with being sold short.

Most fund investors will buy and sell fund shares on the listing exchange or on another secondary market. When buying or selling shares of the fund, investors typically will pay brokerage commissions or other charges imposed by financial intermediaries as determined by that financial intermediary.

Cash Transactions Risk

Cash Transactions Risk: Unlike certain ETFs that distribute portfolio securities entirely in-kind, the fund may effect some or all creations and redemptions using cash, rather than in-kind securities. As a result, an investment in the fund may be less tax-efficient than an investment in an ETF that distributes portfolio securities entirely in-kind.