The fund’s investment objective is to seek capital appreciation.

This table describes the fees and expenses that you may pay when you buy, hold, and sell shares of the fund. Investors may also pay commissions or other fees to their financial intermediaries when they buy, hold, and sell shares of the fund, which are not reflected below.

The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when shares are held in a taxable account. These transaction costs, which are not reflected in “Annual Fund Operating Expenses” or in the “Example,” affect the fund’s performance. During the most recent fiscal year, the fund’s portfolio turnover rate was 50% of the average value of its portfolio.

MFS (Massachusetts Financial Services Company, the fund's investment adviser) normally invests at least 80% of the fund’s net assets in growth companies. MFS defines growth companies as companies that MFS believes have above average potential with respect to the rate and duration of earnings growth compared to other companies. MFS considers a number of factors when determining a company’s growth potential, including whether (i) the issuer is included in an index that is representative of growth companies; (ii) the issuer is classified as a growth company by an independent third party financial data provider; and/or (iii) the issuer exhibits the characteristics of a growth company, considering metrics such as historical and/or projected earnings, sales, or free cash flow growth rates compared to the applicable equity market and/or to issuers in the same sector or industry. In assessing the growth potential of an issuer, MFS may also consider measures of financial quality, such as indicators of profitability (i.e., return on equity and return on invested capital), balance sheet strength (including leverage and interest coverage ratios), an issuer’s research and development expenses relative to sales, and whether an issuer is raising capital to grow, fund, or expand its business. Growth companies tend to have stock prices that are high relative to their earnings, dividends, book value, or other financial measures.

MFS normally invests the fund’s assets primarily in common stocks. Common stocks are equity securities that represent an ownership interest (or right to acquire an ownership interest) in a company or other issuer.

While MFS may invest the fund’s assets in securities of companies of any size, MFS primarily invests in securities of companies with large capitalizations.

MFS may invest the fund’s assets in foreign securities.

MFS normally invests the fund's assets across different industries and sectors, but MFS may invest a significant percentage of the fund's assets in issuers in a single industry or sector.

The fund is a non-diversified fund. This means that MFS may invest a significant percentage of the fund’s assets in a single issuer or a small number of issuers.

MFS uses an active bottom-up investment approach to buying and selling investments for the fund. Investments are selected primarily based on fundamental analysis of individual issuers. Quantitative screening tools that systematically evaluate issuers may also be considered.

For purposes of the fund's 80% policy, net assets include the amount of any borrowings for investment purposes.

The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing how the fund’s performance over time compares with that of (i) a broad measure of market performance and (ii) the performance of an additional index that the adviser believes more closely reflects the market segments in which the fund invests.

The fund’s past performance (before and after taxes) does not necessarily indicate how the fund will perform in the future. Updated performance is available online at mfs.com.

After-tax returns are calculated using the historical highest individual U.S. federal marginal income tax rates and do not reflect the impact of state and local taxes. Your actual after-tax returns will depend on your own tax situation, and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts (IRAs). The after-tax returns are shown for only one of the fund’s classes of shares, and after-tax returns for the fund’s other classes of shares will vary from the returns shown.

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:

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.

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.

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.

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.

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.