Fees and expenses

You may qualify for a sales charge waiver or discount if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund.

Other Expenses, New Fund, Based on Estimates [Text]

“Other expenses” for Class A are based on estimates for the current fiscal year. “Other expenses” include “Acquired fund fees and expenses,” which were less than 0.01% of the average net assets of the Fund.

Shareholder Fees [Table]

	Class A		Class P
Maximum front-end sales charge (load) imposed on purchases (as a % of offering price)	5.50	%	None
Maximum contingent deferred sales charge (load) (CDSC) (as a % of purchase or sales price, whichever is less)	None	1	None

Annual Fund Operating Expenses [Table]

	Class A		Class P
Management fees	0.89	%	0.89	%
Distribution and/or service (12b-1) fees	0.25		None
Other expenses2	0.31		0.31
Total annual fund operating expenses	1.45		1.20
Less management fee waiver/expense reimbursements3	0.20		0.20
Total annual fund operating expenses after management fee waiver/expense reimbursements3	1.25		1.00

1	Purchases of $1 million or more that were not subject to a front-end sales charge are subject to a 1% CDSC if sold within one year of the purchase date.

2	“Other expenses” for Class A are based on estimates for the current fiscal year. “Other expenses” include “Acquired fund fees and expenses,” which were less than 0.01% of the average net assets of the Fund.

3

The Trust, with respect to the Fund, and UBS Asset Management (Americas) LLC, the Fund’s investment advisor and administrator (“UBS AM (Americas)” or the “Advisor”), have entered into a written agreement pursuant to which the Advisor has agreed to waive a portion of its management fees and/or to reimburse expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions, dividend expense and security loan fees for securities sold short and extraordinary expenses, such as proxy-related expenses) to the extent necessary so that the Fund’s ordinary operating expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions, dividend expense and security loan fees for securities sold short and extraordinary expenses, such as proxy-related expenses), through the period ending October 28, 2027, do not exceed 1.25% for Class A shares and 1.00% for Class P shares. Pursuant to the written agreement, the Advisor is entitled to be reimbursed for any fees it waives and expenses it reimburses to the extent such reimbursement can be made during the three years following the period during which such fee waivers and expense reimbursements were made, provided that the reimbursement of the Advisor by the Fund will not cause the Fund to exceed the lesser of any applicable expense limit that is in place for the Fund (i) at the time of the waiver or reimbursement or (ii) at the time of the recoupment. The fee waiver/expense reimbursement agreement may be terminated by the Fund’s Board of Trustees at any time and also will terminate automatically upon the expiration or termination of the Fund’s advisory contract with the Advisor. Upon termination of the fee waiver/expense reimbursement agreement, however, UBS AM (Americas)’s three year recoupment rights will survive.

Expense Example [Heading]

Example

Expense Example, With Redemption [Table]

	1 year			3 years			5 years			10 years
Class A		$	670		$	965		$	1,281		$	2,174
Class P			102			361			640			1,437

Portfolio Turnover [Text Block]

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 Fund shares are held in a taxable account. These 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 43% of the average value of its portfolio.

Expense Heading [Optional Text]

Fees and expenses

Expense Breakpoint Discounts [Text]

You may qualify for a sales charge waiver or discount if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund.

Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]

Since the “Acquired fund fees and expenses” are not directly borne by the Fund, they are not reflected in the Fund’s financial statements, and therefore the amounts listed in “Total annual fund operating expenses” and “Total annual fund operating expenses after management fee waiver/expense reimbursements” will differ from those presented in the Financial highlights.

Shareholder Fees [Table]

	Class A		Class P
Maximum front-end sales charge (load) imposed on purchases (as a % of offering price)	5.50	%	None
Maximum contingent deferred sales charge (load) (CDSC) (as a % of purchase or sales price, whichever is less)	None	1	None

Annual Fund Operating Expenses [Table]

	Class A		Class P
Management fees	0.80	%	0.80	%
Distribution and/or service (12b‑1) fees	0.25		None
Other expenses	0.51		0.49
Acquired fund fees and expenses	0.13		0.13
Total annual fund operating expenses2	1.69		1.42
Less management fee waiver/expense reimbursements3	0.36		0.34
Total annual fund operating expenses after management fee waiver/expense reimbursements2,3	1.33		1.08

1	Purchases of $1 million or more that were not subject to a front-end sales charge are subject to a 1% CDSC if sold within one year of the purchase date.

2

Since the “Acquired fund fees and expenses” are not directly borne by the Fund, they are not reflected in the Fund’s financial statements, and therefore the amounts listed in “Total annual fund operating expenses” and “Total annual fund operating expenses after management fee waiver/expense reimbursements” will differ from those presented in the Financial highlights.

3

The Trust, with respect to the Fund, and UBS Asset Management (Americas) LLC, the Fund’s investment advisor and administrator (“UBS AM (Americas)” or the “Advisor”), have entered into a written agreement pursuant to which the Advisor has agreed to waive a portion of its management fees and/or to reimburse expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions, dividend expense and security loan fees for securities sold short and extraordinary expenses, such as proxy-related expenses) to the extent necessary so that the Fund’s operating expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions, dividend expense and security loan fees for securities sold short and extraordinary expenses, such as proxy-related expenses), through the period ending October 28, 2027, do not exceed 1.20% for Class A shares and 0.95% for Class P shares. Pursuant to the written agreement, the Advisor is entitled to be reimbursed for any fees it waives and expenses it reimburses to the extent such reimbursement can be made during the three years following the period during which such fee waivers and expense reimbursements were made, provided that the reimbursement of the Advisor by the Fund will not cause the Fund to exceed the lesser of any applicable expense limit that is in place for the Fund (i) at the time of the waiver or reimbursement or (ii) at the time of the recoupment. The fee waiver/expense reimbursement agreement may be terminated by the Fund’s Board of Trustees at any time and also will terminate automatically upon the expiration or termination of the Fund’s advisory contract with the Advisor. Upon termination of the fee waiver/expense reimbursement agreement, however, UBS AM (Americas)’s three year recoupment rights will survive.

Expense Example [Heading]

Example

Expense Example, With Redemption [Table]

	1 year			3 years			5 years			10 years
Class A		$	678		$	1,020		$	1,385		$	2,410
Class P			110			416			744			1,673

Portfolio Turnover [Text Block]

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 Fund shares are held in a taxable account. These 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 77% of the average value of its portfolio, including TBA transactions, and 44% of the average value of its portfolio, excluding TBA transactions.

Expense Heading [Optional Text]

Fees and expenses

Expense Breakpoint Discounts [Text]

You may qualify for a sales charge waiver or discount if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund.

Shareholder Fees Caption [Optional Text]

Shareholder fees (fees paid directly from your investment)

Operating Expenses Caption [Optional Text]

Annual fund operating expenses (expenses that you pay each year as a percentage of the value of your investment)

Expenses Deferred Charges [Text Block]

Purchases of $1 million or more that were not subject to a front-end sales charge are subject to a 1% CDSC if sold within one year of the purchase date.

Expense Example Narrative [Text Block]

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then sell all of your shares at the end of those periods unless otherwise stated. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. The costs described in the example reflect the expenses of the Fund that would result from the irrevocable fee waiver and expense reimbursement for all

years. Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Portfolio Turnover [Heading]

Portfolio turnover

Portfolio Turnover, Rate

31.00%

Prospectus [Line Items]

Expense Narrative [Text Block]

These tables describe the fees and expenses that you may pay if you buy, hold, and sell shares of the Fund. You may qualify for a sales charge waiver or discount if you and your family invest, or agree to invest in the future, at least $100,000 in the Fund. More information about these and other discounts and waivers, as well as eligibility requirements for each share class, is available from your financial advisor and in “Managing your fund account” beginning on page 112 of this prospectus and in “Reduced sales charges, additional purchase, exchange and redemption information and other services” beginning on page 97 of the Fund’s statement of additional information (“SAI”). In addition to the fees and expenses described below, you may also be required to pay commissions or other fees to your broker for transactions in Class P shares. Shares of the Fund are available in classes other than Class P that have different fees and expenses.

Different intermediaries and financial professionals may make available different sales charge waivers or discounts. These variations are described in Appendix A beginning on page A‑1 of this prospectus.

Expense Breakpoint, Minimum Investment Required [Amount]

$ 100,000

Shareholder Fees [Table]

	Class A		Class P
Maximum front-end sales charge (load) imposed on purchases (as a % of offering price)	3.75	%	None
Maximum contingent deferred sales charge (load) (CDSC) (as a % of purchase or sales price, whichever is less)	None	1	None

Annual Fund Operating Expenses [Table]

	Class A		Class P
Management fees	0.50	%	0.50	%
Distribution and/or service (12b‑1) fees	0.25		None
Other expenses2	0.67		0.71
Total annual fund operating expenses	1.42		1.21
Less management fee waiver/expense reimbursements3	0.52		0.56
Total annual fund operating expenses after management fee waiver/expense reimbursements3	0.90		0.65

1	Purchases of $1 million or more that were not subject to a front-end sales charge are subject to a 1% CDSC if sold within one year of the purchase date.

2	“Other expenses” include “Acquired fund fees and expenses,” which were less than 0.01% of the average net assets of the Fund.

3

The Trust, with respect to the Fund, and UBS Asset Management (Americas) LLC, the Fund’s investment advisor and administrator (“UBS AM (Americas)” or the “Advisor”), have entered into a written agreement pursuant to which the Advisor has agreed to waive a portion of its management fees and/or to reimburse expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions, dividend expense and security loan fees for securities sold short, and extraordinary expenses, such as proxy-related expenses) to the extent necessary so that the Fund’s ordinary operating expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions, dividend expense and security loan fees for securities sold short, and extraordinary expenses, such as proxy-related expenses), through the period ending October 28, 2027, do not exceed 0.90% for Class A shares and 0.65% for Class P shares. Pursuant to the written agreement, the Advisor is entitled to be reimbursed for any fees it waives and expenses it reimburses to the extent such reimbursement can be made during the three years following the period during which such fee waivers and expense reimbursements were made, provided that the reimbursement of the Advisor by the Fund will not cause the Fund to exceed the lesser of any applicable expense limit that is in place for the Fund (i) at the time of the waiver or reimbursement or (ii) at the time of the recoupment. The fee waiver/expense reimbursement agreement may be terminated by the Fund’s Board of Trustees at any time and also will terminate automatically upon the expiration or termination of the Fund’s advisory contract with the Advisor. Upon termination of the fee waiver/expense reimbursement agreement, however, UBS AM (Americas)’s three year recoupment rights will survive.

Expense Example [Heading]

Example

Expense Example, With Redemption [Table]

	1 year			3 years			5 years			10 years
Class A		$	463		$	758		$	1,075		$	1,970
Class P			66			329			611			1,416

Portfolio Turnover [Text Block]

The Fund pays transaction costs, such as mark-ups, 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 Fund shares are held in a taxable account. These 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 295% of the average value of its portfolio, including TBA transactions, and 38% of the average value of its portfolio, excluding TBA transactions.

Expense Heading [Optional Text]

Fees and expenses

Other Expenses, New Fund, Based on Estimates [Text]

“Other expenses” for Class A are based on estimates for the current fiscal year. “Other expenses” include “Acquired fund fees and expenses,” which were less than 0.01% of the average net assets of the Fund.

Shareholder Fees [Table]

	Class A		Class P
Maximum front-end sales charge (load) imposed on purchases (as a % of offering price)	None		None
Maximum contingent deferred sales charge (load) (CDSC) (as a % of purchase or sales price, whichever is less)	None	1	None

Annual Fund Operating Expenses [Table]

	Class A		Class P
Management fees	0.15	%	0.15	%
Distribution and/or service (12b‑1) fees	0.10		None
Other expenses2	0.54		0.54
Total annual fund operating expenses	0.79		0.69
Less management fee waiver/expense reimbursements3	0.44		0.44
Total annual fund operating expenses after management fee waiver/expense reimbursements3	0.35		0.25

1

Shares of the Fund acquired through the exchange of shares of another Family Fund (“Family Funds” include PACE® Select funds, series of The UBS Funds and other funds for which UBS AM (US) serves as principal underwriter) may be subject to a deferred sales charge if you later sell the Fund shares acquired in the exchange, based on the terms of the shares of the Family Fund you originally held.

2	“Other expenses” for Class A are based on estimates for the current fiscal year. “Other expenses” include “Acquired fund fees and expenses,” which were less than 0.01% of the average net assets of the Fund.

3

The Trust, with respect to the Fund, and UBS Asset Management (Americas) LLC, the Fund’s investment advisor and administrator (“UBS AM (Americas)” or the “Advisor”), have entered into a written agreement pursuant to which the Advisor has agreed to waive a portion of its management fees and/or to reimburse expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions, dividend expense and security loan fees for securities sold short and extraordinary expenses, such as proxy-related expenses) to the extent necessary so that the Fund’s ordinary operating expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions, dividend expense and security loan fees for securities sold short and extraordinary expenses, such as proxy-related expenses), through the period ending October 28, 2027, do not exceed 0.35% for Class A shares and 0.25% for Class P shares. Pursuant to the written agreement, the Advisor is entitled to be reimbursed for any fees it waives and expenses it reimburses to the extent such reimbursement can be made during the three years following the period during which such fee waivers and expense reimbursements were made, provided that the reimbursement of the Advisor by the Fund will not cause the Fund to exceed the lesser of any applicable expense limit that is in place for the Fund (i) at the time of the waiver or reimbursement or (ii) at the time of the recoupment. The fee waiver/expense reimbursement agreement may be terminated by the Fund’s Board of Trustees at any time and also will terminate automatically upon the expiration or termination of the Fund’s advisory contract with the Advisor. Upon termination of the fee waiver/expense reimbursement agreement, however, UBS AM (Americas)’s three year recoupment rights will survive.

Expense Example Narrative [Text Block]

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then sell all of your shares at the end of those periods unless otherwise stated. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. The costs described in the example reflect the expenses of the Fund that would result from the contractual fee waiver and expense reimbursement agreement with the Advisor for the first year only. Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Portfolio Turnover [Heading]

Portfolio turnover

Portfolio Turnover, Rate

40.00%

Prospectus [Line Items]

Expense Narrative [Text Block]

These tables describe the fees and expenses that you may pay if you buy, hold, and sell shares of the Fund. In addition to the fees and expenses described below, you also may be required to pay commissions or other fees to your broker for transactions in Class P shares.

Shareholder Fees [Table]

	Class P
Maximum front-end sales charge (load) imposed on purchases (as a % of offering price)	None
Maximum contingent deferred sales charge (load) (CDSC) (as a % of purchase or sales price, whichever is less)	None

Annual Fund Operating Expenses [Table]

	Class P
Management fees	0.50	%
Distribution and/or service (12b-1) fees	None
Other expenses1	0.28
Total annual fund operating expenses	0.78
Less management fee waiver/expense reimbursements2	0.13
Total annual fund operating expenses after management fee waiver/expense reimbursements2	0.65

1	“Other expenses” include “Acquired fund fees and expenses,” which were less than 0.01% of the average net assets of the Fund.

2

The Trust, with respect to the Fund, and UBS Asset Management (Americas) LLC, the Fund’s investment advisor and administrator (“UBS AM (Americas)” or the “Advisor”), have entered into a written agreement pursuant to which the Advisor has agreed to waive a portion of its management fees and/or to reimburse expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions, dividend expense and security loan fees for securities sold short, and extraordinary expenses, such as proxy-related expenses) to the extent necessary so that the Fund’s ordinary operating expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions, dividend expense and security loan fees for securities sold short, and extraordinary expenses, such as proxy-related expenses), through the period ending October 28, 2027, do not exceed 0.65% for Class P shares. Pursuant to the written agreement, the Advisor is entitled to be reimbursed for any fees it waives and expenses it reimburses to the

extent such reimbursement can be made during the three years following the period during which such fee waivers and expense reimbursements were made, provided that the reimbursement of the Advisor by the Fund will not cause the Fund to exceed the lesser of any applicable expense limit that is in place for the Fund (i) at the time of the waiver or reimbursement or (ii) at the time of the recoupment. The fee waiver/expense reimbursement agreement may be terminated by the Fund’s Board of Trustees at any time and also will terminate automatically upon the expiration or termination of the Fund’s advisory contract with the Advisor. Upon termination of the fee waiver/expense reimbursement agreement, however, UBS AM (Americas)’s three year recoupment rights will survive.

Expense Example Narrative [Text Block]

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then sell all of your shares at the end of those periods unless otherwise stated. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. The costs described in the example reflect the expenses of the Fund that would result from the contractual fee waiver and expense reimbursement agreement with the Advisor for the first year only. Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Portfolio Turnover [Heading]

Portfolio turnover

Portfolio Turnover, Rate

28.00%

Prospectus [Line Items]

Expense Narrative [Text Block]

These tables describe the fees and expenses that you may pay if you buy, hold, and sell shares of the Fund. In addition to the fees and expenses described below, you also may be required to pay commissions or other fees to your broker for transactions in Class P shares.

Shareholder Fees [Table]

	Class P
Maximum front-end sales charge (load) imposed on purchases (as a % of offering price)	None
Maximum contingent deferred sales charge (load) (CDSC) (as a % of purchase or sales price, whichever is less)	None

Annual Fund Operating Expenses [Table]

	Class P
Management fees	0.50	%
Distribution and/or service (12b-1) fees	None
Other expenses1	0.25
Total annual fund operating expenses	0.75
Less management fee waiver/expense reimbursements2	0.10
Total annual fund operating expenses after management fee waiver/expense reimbursements2	0.65

1	“Other expenses” include “Acquired fund fees and expenses,” which were less than 0.01% of the average net assets of the Fund.

2

The Trust, with respect to the Fund, and UBS Asset Management (Americas) LLC, the Fund’s investment advisor and administrator (“UBS AM (Americas)” or the “Advisor”), have entered into a written agreement pursuant to which the Advisor has agreed to waive a portion of its management fees and/or to reimburse expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions, dividend expense and security loan fees for securities sold short, and extraordinary expenses, such as proxy-related expenses) to the extent necessary so that the Fund’s ordinary operating expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions, dividend expense and security loan fees for securities sold short, and extraordinary expenses, such as proxy-related expenses), through the period ending October 28, 2027, do not exceed 0.65% for Class P shares. Pursuant to the written agreement, the Advisor is

entitled to be reimbursed for any fees it waives and expenses it reimburses to the extent such reimbursement can be made during the three years following the period during which such fee waivers and expense reimbursements were made, provided that the reimbursement of the Advisor by the Fund will not cause the Fund to exceed the lesser of any applicable expense limit that is in place for the Fund (i) at the time of the waiver or reimbursement or (ii) at the time of the recoupment. The fee waiver/expense reimbursement agreement may be terminated by the Fund’s Board of Trustees at any time and also will terminate automatically upon the expiration or termination of the Fund’s advisory contract with the Advisor. Upon termination of the fee waiver/expense reimbursement agreement, however, UBS AM (Americas)’s three year recoupment rights will survive.

Expense Example Narrative [Text Block]

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then sell all of your shares at the end of those periods unless otherwise stated. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. The costs described in the example reflect the expenses of the Fund that would result from the contractual fee waiver and expense reimbursement agreement with the Advisor for the first year only. Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Portfolio Turnover [Heading]

Portfolio turnover

Portfolio Turnover, Rate

36.00%

Prospectus [Line Items]

Expense Narrative [Text Block]

These tables describe the fees and expenses that you may pay if you buy, hold, and sell shares of the Fund. Shares of Class P2 are available for purchase on behalf of clients of a fee-based program or certain other advisory programs in which UBS Asset Management (Americas) LLC, the Fund’s investment advisor and administrator (“UBS AM (Americas)” or the “Advisor”) exercises investment discretion. Clients pay a wrap fee or a similar advisory fee to participate in such programs. Shares of Class P2 are also available for purchase on behalf of institutional clients with which the Advisor or its affiliates has signed a separate investment management agreement, pursuant to which such clients pay an advisory fee.

Shareholder Fees [Table]

	Class P2
Maximum front-end sales charge (load) imposed on purchases (as a % of offering price)		None
Maximum contingent deferred sales charge (load) (CDSC) (as a % of purchase or sales price, whichever is less)		None

Annual Fund Operating Expenses [Table]

	Class P2
Management fees		0.89	%
Distribution and/or service (12b‑1) fees		None
Other expenses1		0.32
Total annual fund operating expenses		1.21
Less management fee waiver/expense reimbursements2		0.95
Total annual fund operating expenses after management fee waiver/expense reimbursements2		0.26

1	“Other expenses” include “Acquired fund fees and expenses,” which were less than 0.01% of the average net assets of the Fund.

2

The Trust, with respect to the Fund, and the Advisor have entered into a written agreement pursuant to which the Advisor has agreed to (i) waive its management fees and retained administration fees, and (ii) reimburse expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions, dividend expense and security loan fees for securities sold short, and extraordinary expenses, such as proxy-related expenses) to the extent necessary so that the Fund’s ordinary operating expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions, dividend expense and security loan fees for securities sold short, and extraordinary expenses, such as proxy-related expenses) through the period ending October 28, 2027 do not exceed 0.40% for Class P2 shares. Pursuant to the written agreement, the Advisor is entitled to be reimbursed for any fees it waives and expenses it reimburses to the extent such reimbursement can be made during the three years following the period during which such fee waivers and expense reimbursements were made, provided that the reimbursement of the Advisor by the Fund will not cause the Fund to exceed the lesser of any applicable expense limit that is in place for the Fund (i) at the time of the waiver or reimbursement or (ii) at the time of the recoupment. The fee waiver/expense reimbursement agreement may be terminated by the Fund’s Board of Trustees at any time and also will terminate automatically upon the expiration or termination of the Fund’s advisory contract with the Advisor. Upon termination of the fee waiver/expense reimbursement agreement, however, UBS AM (Americas)’s three year recoupment rights will survive.

Expense Example Narrative [Text Block]

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then sell all of your shares at the end of those periods unless otherwise stated. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. The costs described in the example reflect the expenses of the Fund that would result from the contractual fee waiver and expense reimbursement agreement with the Advisor for the first year only. Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Portfolio Turnover [Heading]

Portfolio turnover

Portfolio Turnover, Rate

43.00%

Prospectus [Line Items]

Expense Narrative [Text Block]

These tables describe the fees and expenses that you may pay if you buy, hold, and sell shares of the Fund. Shares of Class P2 are available for purchase on behalf of clients of a fee-based program or certain other advisory programs in which UBS Asset Management (Americas) LLC, the Fund’s investment advisor and administrator (“UBS AM (Americas)” or the “Advisor”) exercises investment discretion. Clients pay a wrap fee or a similar advisory fee to participate in such programs. Shares of Class P2 are also available for purchase on behalf of institutional clients with which the Advisor or its affiliates has signed a separate investment management agreement, pursuant to which such clients pay an advisory fee.

Shareholder Fees [Table]

	Class P2
Maximum front-end sales charge (load) imposed on purchases (as a % of offering price)		None
Maximum contingent deferred sales charge (load) (CDSC) (as a % of purchase or sales price, whichever is less)		None

Annual Fund Operating Expenses [Table]

	Class P2
Management fees		0.80	%
Distribution and/or service (12b‑1) fees		None
Other expenses1,2		0.46
Total annual fund operating expenses		1.26
Less management fee waiver/expense reimbursements3		1.00
Total annual fund operating expenses after management fee waiver/expense reimbursements3		0.26

1	“Other expenses” include “Acquired fund fees and expenses,” which were less than 0.01% of the average net assets of the Fund.

2	“Other expenses” include interest expense of 0.01%.

3

The Trust, with respect to the Fund, and the Advisor have entered into a written agreement pursuant to which the Advisor has agreed to (i) waive its management fees and retained administration fees, and (ii) reimburse expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions, dividend expense and security loan fees for securities sold short, and extraordinary expenses, such as proxy-related expenses) to the extent necessary so that the Fund’s ordinary operating expenses (excluding expenses incurred through investment in other investment companies, interest, taxes, brokerage commissions, dividend expense and security loan fees for securities sold short, and extraordinary expenses, such as proxy-related expenses) through the period ending October 28, 2027 do not exceed 0.25% for Class P2 shares. Pursuant to the written agreement, the Advisor is entitled to be reimbursed for any fees it waives and expenses it reimburses to the extent such reimbursement can be made during the three years following the period during which such fee waivers and expense reimbursements were made, provided that the reimbursement of the Advisor by the Fund will not cause the Fund to exceed the lesser of any applicable expense limit that is in place for the Fund (i) at the time of the waiver or reimbursement or (ii) at the time of the recoupment. The fee waiver/expense reimbursement agreement may be terminated by the Fund’s Board of Trustees at any time and also will terminate automatically upon the expiration or termination of the Fund’s advisory contract with the Advisor. Upon termination of the fee waiver/expense reimbursement agreement, however, UBS AM (Americas)’s three year recoupment rights will survive.

Expense Example Narrative [Text Block]

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then sell all of your shares at the end of those periods unless otherwise stated. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. The costs described in the example reflect the expenses of the Fund that would result from the contractual fee waiver and expense reimbursement agreement with the Advisor for the first year only. Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Portfolio Turnover [Heading]

Portfolio turnover

Portfolio Turnover, Rate

31.00%

Prospectus [Line Items]

Expense Narrative [Text Block]

These tables describe the fees and expenses that you may pay if you buy, hold, and sell shares of the Fund. Shares of Class P2 are available for purchase on behalf of clients of a fee-based program or certain other advisory programs in which UBS Asset Management (Americas) LLC, the Fund’s investment advisor and administrator (“UBS AM (Americas)” or the “Advisor”) exercises investment discretion. Clients pay a wrap fee or a similar advisory fee to participate in such programs. Shares of Class P2 are also available for purchase on behalf of institutional clients with which the Advisor or its affiliates has signed a separate investment management agreement, pursuant to which such clients pay an advisory fee.

Shareholder Fees Caption [Optional Text]

Shareholder fees (fees paid directly from your investment)

Operating Expenses Caption [Optional Text]

Annual fund operating expenses (expenses that you pay each year as a percentage of the value of your investment)

Expense Example [Heading]

Example

Expense Example, With Redemption [Table]

		1 year				3 years				5 years				10 years
Class P2			$31				$201				$386				$921

Portfolio Turnover [Text Block]

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 Fund shares are held in a taxable account. These 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 28% of the average value of its portfolio.

Expense Heading [Optional Text]

Fees and expenses

Shareholder Fees Caption [Optional Text]

Shareholder fees (fees paid directly from your investment)

Operating Expenses Caption [Optional Text]

Annual fund operating expenses (expenses that you pay each year as a percentage of the value of your investment)

Expense Example [Heading]

Example

Expense Example, With Redemption [Table]

		1 year				3 years				5 years				10 years
Class P2			$20				$245				$488				$1,184

Portfolio Turnover [Text Block]

The Fund pays transaction costs, such as mark-ups, 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 Fund shares are held in a taxable account. These 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 295% of the average value of its portfolio, including TBA transactions, and 38% of the average value of its portfolio, excluding TBA transactions.

Expense Heading [Optional Text]

Fees and expenses

Shareholder Fees Caption [Optional Text]

Shareholder fees (fees paid directly from your investment)

Operating Expenses Caption [Optional Text]

Annual fund operating expenses (expenses that you pay each year as a percentage of the value of your investment)

Expense Example [Heading]

Example

Expense Example, With Redemption [Table]

		1 year				3 years				5 years				10 years
Class P2			$15				$171				$340				$830

Portfolio Turnover [Text Block]

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 Fund shares are held in a taxable account. These 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 40% of the average value of its portfolio.