UBS RMA Money Market Portfolio U.S. Government Portfolio Tax-Free Fund California Municipal Money Fund New York Municipal Money Fund

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UBS RMA

Money Market Portfolio

U.S. Government Portfolio

Tax-Free Fund

California Municipal Money Fund

New York Municipal Money Fund

Prospectus

August 28, 2015

Ticker symbols:

Money Market Portfolio RMAXX

U.S. Government Portfolio RUSXX

Tax-Free Fund RTFXX

California Municipal Money Fund RCAXX New York Municipal Money Fund RNYXX

Not FDIC Insured. May lose value. No bank guarantee.

Money Market Funds Prospectus

This prospectus offers shares of these money market funds primarily to participants in the UBS Financial Services Inc. Resource Management Account^®(RMA^®) Program, the UBS Financial Services Inc. Business Services Account BSA^®Program and certain UBS Financial Services Inc. advisory programs.

As with all mutual funds, the Securities and Exchange Commission has not approved or disapproved the funds’ shares or determined whether this prospectus is complete or accurate. To state otherwise is a crime.

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UBS Global Asset Management UBS RMA

Management . . . Page 29 Dividends and taxes . . . Page 30 Disclosure of portfolio holdings . . . Page 31 Disclosure of market-based net asset values . . . Page 32 Financial highlights . . . Page 33 Where to learn more about the funds . . . Back cover Please find the UBS family of funds privacy notice on page 39. Please find the UBS Global Asset

Management business continuity planning overviewon page 40. The funds are not complete or balanced investment programs.

2

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Money Market Portfolio

Fund summary

3 Investment objective

Maximum current income consistent with liquidity and conservation of capital.

Fees and expenses

These tables describe the fees and expenses that you may pay if you buy and hold shares of the fund. Shareholder transaction expenses (fees paid directly from your investment):

Maximum front-end sales charge (load) imposed on purchases

(as a % of offering price) None

Maximum deferred sales charge (load) (as a % of offering price) None Maximum account fee

UBS Financial Services Inc. RMA Program $150

UBS Financial Services Inc. Business Services Account BSA Program $150 UBS Financial Services Inc. Basic Investment Account Program $ 75

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

Management fees 0.37%

Service (12b-1) fees None

Other expenses 0.20

Service (non-12b-1) fees 0.15

Miscellaneous expenses 0.05

Total annual fund operating expenses 0.57

Management fee waiver¹ 0.02

Total annual fund operating expenses after

fee waiver¹ 0.55

1 The fund and UBS Global Asset Management (Americas) Inc. (“UBS Global AM”) have contractually agreed to cap the fund’s aggregate management and shareholder services fees (paid pursuant to the related shareholder services plan) so that the total of these fees does not exceed 0.50% of the fund’s average daily net assets. This cap results in an effective investment advisory and ad- ministration fee rate not to exceed 0.35% of the fund’s average daily net assets. The contractual cap continues for as long as the fund’s shareholder services plan remains in effect.

Example

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. The example also assumes that your investment has a 5% return each year and that the fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

1 yr. 3 yrs. 5 yrs. 10 yrs.

Money Market Portfolio $56 $181 $316 $712

This example does not reflect the above referenced program fees.

Principal strategies Principal investments

The fund is a money market fund and seeks to maintain a stable price of $1.00 per share. To do this, the fund invests in a diversified portfolio of high quality money market instruments of governmental and private issuers. Money market instruments generally are short-term debt obligations and similar securities. They also may include longer-term bonds that have variable interest rates or other special features that give them the financial characteristics of short-term debt. The fund invests in foreign money market instruments only if they are denominated in US dollars.

Management process

UBS Global Asset Management (Americas) Inc. (“UBS Global AM”) acts as the fund’s investment advisor. As investment advisor, UBS Global AM makes the fund’s investment decisions. UBS Global AM selects money market instruments for the fund based on its assessment of relative values and changes in market and economic conditions. UBS Global AM considers safety of principal and liquidity in selecting securities for the fund and thus may not buy securities that pay the highest yield.

UBS Global Asset Management

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Principal risks

All investments carry a certain amount of risk, and the fund cannot guarantee that it will achieve its investment objective. While the fund seeks to maintain the value of your investment at $1.00 per share, you may lose money by investing in the fund. An investment in the fund is not a bank deposit and is neither insured nor guaranteed by the Federal Deposit Insurance Corpora- tion or any other government agency. Money market instruments generally have a low risk of loss, but they are not risk-free. The principal risks presented by an investment in the fund are:

Credit risk: Issuers of money market instruments may fail to make payments when due, or they may become less willing or less able to do so.

Interest rate risk: The value of the fund’s investments generally will fall when short-term interest rates rise, and its yield will tend to lag behind prevailing rates. The risks associated with rising interest rates may be more pronounced going forward due to the anticipated end of an extended period of historically low rates.

Market risk: The risk that the market value of the fund’s investments may fluctuate, sometimes rapidly or unpredictably, as the markets fluctuate, which may affect the fund’s ability to maintain a $1.00 share price. Market risk may affect a single issuer, industry, or sector of the economy, or it may affect the market as a whole. Moreover, changing market, economic and political conditions in one country or geographic region could adversely impact market, economic and political conditions in other countries or regions.

Foreign investing risk: The value of the fund’s invest- ments in foreign securities may fall due to adverse political, social and economic developments abroad.

However, because the fund’s foreign investments must be denominated in US dollars, it generally is not subject to the risk of changes in currency valuations.

US Government securities risk: There are different types of US government securities with different levels of credit risk, including the risk of default, depending on the nature of the particular government support for

that security. For example, a US government-sponsored entity, such as Federal National Mortgage Association (“Fannie Mae”) or Federal Home Loan Mortgage Cor- poration (“Freddie Mac”), although chartered or sponsored by an Act of Congress, may issue securities that are neither insured nor guaranteed by the US Treasury and are therefore riskier than those that are.

Liquidity risk: Although the fund invests in a diversi- fied portfolio of high quality instruments, the fund’s investments may become less liquid as a result of market developments or adverse investor perception. Management risk: The risk that the investment strate- gies, techniques and risk analyses employed by the advisor may not produce the desired results.

Money market fund regulatory risk: The US Securi- ties and Exchange Commission (“SEC”) adopted changes to the rules that govern SEC registered money market funds in July 2014 that will affect the manner in which money market funds are structured and oper- ated. In addition, the SEC proposed additional regulatory changes, the final terms of which are yet to be determined. These changes may affect the investment strategies, performance, yield, operating expenses and continued viability of the fund. As of the date of this prospectus, UBS Global AM is evaluating the potential impact of these regulatory changes and expects to up- date investors in the future as the regulatory compli- ance deadlines approach.

Performance

Risk/return bar chart and table

The following bar chart and table provide information about the fund’s performance and thus give some indi- cation of the risks of an investment in the fund. The bar chart shows how the fund’s performance has varied from year to year. The table that follows the bar chart shows the average annual returns over various time periods for the fund’s shares.

The fund’s past performance does not necessarily indi- cate how the fund will perform in the future.

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5 Average annual total returns

(for the periods ended December 31, 2014)

One year 0.01%

Five years 0.01

Ten years 1.44

Investment advisor

UBS Global Asset Management (Americas) Inc. (“UBS Global AM”) serves as the investment advisor to the fund.

Purchase & sale of fund shares

You must be a client of UBS Financial Services Inc. or a client of certain affiliated firms to purchase fund shares. You may purchase or sell fund shares by contacting your Financial Advisor. The fund has a $5,000 minimum investment requirement for investors purchasing shares of the fund by withdrawing from certain deposit account sweep arrangements. The fund has no minimum to add to an account. Shares of the fund may be purchased or redeemed through your Financial Advisor on any business day on which the Boston offices of the fund’s custodian and the New York City offices of UBS Financial Services Inc. and its bank are all open for business.

Tax information

The dividends and distributions you receive from the fund are taxable and will generally be taxed as ordinary income, capital gains or some combination of both. If you hold shares through a tax-exempt account or plan, such as an individual retirement account or 401(k) plan, dividends and distributions on your shares generally will not be subject to tax before distributions are made to you from the account or plan.

Payments to broker-dealers and other financial intermediaries

If you purchase the fund through a broker-dealer or other financial intermediary (such as a bank), the fund and its related companies may pay the intermediary for the sale of fund shares and related services. These payments may create a conflict of interest by influencing the broker-dealer or other intermediary and your Finan- cial Advisor to recommend the fund over another investment. Ask your Financial Advisor or visit your financial intermediary’s Web site for more information.

UBS Global Asset Management Total Return

Total return January 1 to June 30, 2015: 0.00% (Actual total return was 0.0050%) Best quarter during years shown—4Q 2006: 1.21%

Worst quarters during years shown—3Q 2009; 1Q, 2Q & 3Q 2010; & 1Q 2011: 0.00% (Actual total returns were 0.0024%)

Updated performance information is available by contacting your Financial Advisor or by calling 1-888-793 8637 (Option #1).

06

0 1 4 3 5

2 6%

‘07 ‘08 ‘09

‘06

‘05 ‘10 ‘11 ‘12 ‘13 ‘14

4.76% 4.76%

2.32% 2.32% 2.69%

2.69%

4.55% 4.55%

0.01%

0.01% 0.01%0.01% 0.01%0.01% 0.01%0.01% 0.01%0.01% 0.16%

0.16%

UBS RMA Money Market Portfolio Annual Total Returns

Calendar Year

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U.S. Government Portfolio

Fund summary

6

Investment objective

Maximum current income consistent with liquidity and conservation of capital.

UBS Financial Services Inc. Business Services Account BSA Program $150

Service (12b-1) fees 0.15

Other expenses 0.04

Example

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. The example also assumes that your investment has a 5% return each year and that the fund’s operating expenses remain the same.

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

1 yr. 3 yrs. 5 yrs. 10 yrs.

U.S. Government Portfolio $57 $179 $313 $701

The fund is a money market fund and seeks to maintain a stable price of $1.00 per share. To do this, the fund invests in a diversified portfolio of high quality, US government money market instruments and in related repurchase agreements.

Money market instruments generally are short-term debt obligations and similar securities. They also may include longer-term bonds that have variable interest rates or other special features that give them the financial characteristics of short-term debt. The fund has adopted a policy to invest 99.5% or more of its total assets in cash, government securities, and/or repurchase agree- ments that are collateralized fully (i.e., collateralized by cash and/or government securities) in order to qualify as a “government money market fund” under federal reg- ulations. In addition, under normal circumstances, the fund invests at least 80% of its net assets in US government securities, including government securities subject to repurchase agreements. Many US government money market instruments pay income that is generally exempt from state and local income tax, although it may be subject to corporate franchise tax in some states.

The fund may invest a significant percentage of its assets in repurchase agreements. Repurchase agreements are transactions in which the fund purchases government securities and simultaneously commits to resell them to the same counterparty at a future time and at a price reflecting a market rate of interest. Income from repurchase agreements may not be exempt from state and local income taxation. Repurchase agreements of- ten offer a higher yield than investments directly in government securities. In deciding whether an investment in a repurchase agreement is more attractive than a direct investment in government securities, the fund considers the possible loss of this tax advantage.

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7 Management process

UBS Global Asset Management (Americas) Inc. (“UBS Global AM”) acts as the fund’s investment advisor. As investment advisor, UBS Global AM makes the fund’s investment decisions. UBS Global AM selects money market instruments for the fund based on its assessment of relative values and changes in market and economic conditions.

Principal risks

Market risk: The risk that the market value of the fund’s investments may fluctuate, sometimes rapidly or unpredictably, as the markets fluctuate, which may affect the fund’s ability to maintain a $1.00 share price. Market risk may affect a single issuer, industry, or sector of the economy, or it may affect the market as a whole. Moreover, changing market, economic and political conditions in one country or geographic region could adversely impact market, economic and political conditions in other countries or regions.

US Government securities risk: There are different types of US government securities with different levels of credit risk, including the risk of default, depending on the nature of the particular government support for that security. For example, a US government-sponsored entity, such as Federal National Mortgage Association (“Fannie Mae”) or Federal Home Loan Mortgage Cor- poration (“Freddie Mac”), although chartered or sponsored by an Act of Congress, may issue securities that are neither insured nor guaranteed by the US Treasury and are therefore riskier than those that are.

Interest rate risk: The value of the fund’s investments generally will fall when short-term interest rates rise,

and its yield will tend to lag behind prevailing rates. The risks associated with rising interest rates may be more pronounced going forward due to the anticipated end of an extended period of historically low rates. Liquidity risk: Although the fund invests in a diversi- fied portfolio of high quality instruments, the fund’s investments may become less liquid as a result of market developments or adverse investor perception.

Management risk: The risk that the investment strate- gies, techniques and risk analyses employed by the advisor may not produce the desired results.

Performance

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Average annual total returns

One year 0.01%

Five years 0.01

Ten years 1.25

You must be a client of UBS Financial Services Inc. or a client of certain affiliated firms to purchase fund shares. You may purchase or sell fund shares by contacting your Financial Advisor. The fund has a $5,000 minimum investment requirement for investors purchasing shares of the fund by withdrawing from certain deposit account sweep arrangements. The fund has no minimum to add to an account. Shares of the fund may be purchased or redeemed through your Financial Advisor on any business day on which the Boston offices of the fund’s custodian and the New York City offices of UBS Financial Services Inc. and its bank are all open for business.

Tax information

The dividends and distributions you receive from the fund are taxable and will generally be taxed as ordinary income, capital gains or some combination of both. If you hold shares through a tax-exempt account or plan, such as an individual retirement account or 401(k) plan, dividends and distributions on your shares generally will not be subject to tax before distributions are made to you from the account or plan.

If you purchase the fund through a broker-dealer or other financial intermediary (such as a bank), the fund and its related companies may pay the intermediary for the sale of fund shares and related services. These payments may create a conflict of interest by influencing the broker-dealer or other intermediary and your Finan- cial Advisor to recommend the fund over another investment. Ask your Financial Advisor or visit your financial intermediary’s Web site for more information.

Worst quarters during years shown—2Q & 3Q 2009; 1Q, 2Q & 3Q 2010; & 1Q 2011: 0.00% (Actual total returns were 0.0024%)

06

0 1 4 3 5

2 6%

‘07 ‘08 ‘09

‘06

‘05 ‘10 ‘11 ‘12 ‘13 ‘14

4.32% 4.32%

1.44% 1.44% 2.50%

2.50%

4.33% 4.33%

0.01%

0.01% 0.01%0.01% 0.01%0.01% 0.01%0.01% 0.01%0.01% 0.03%

0.03%

UBS RMA U.S. Government Portfolio Annual Total Returns

Calendar Year

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Tax-Free Fund

Fund summary

Maximum current income exempt from federal income tax consistent with liquidity and conservation of capital. Fees and expenses

Other expenses 0.05

Example

1 yr. 3 yrs. 5 yrs. 10 yrs.

Tax-Free Fund $60 $189 $329 $738

The fund is a money market fund and seeks to maintain a stable price of $1.00 per share. To do this, the fund invests in a diversified portfolio of high quality, municipal money market instruments.

Money market instruments generally are short-term debt obligations and similar securities. They also may include longer-term bonds that have variable interest rates or other special features that give them the financial characteristics of short-term debt. Under normal circumstances, the fund will invest at least 80% of its net assets in investments, the income from which is exempt from federal income tax. While the fund normally does not do so, it may invest in securities that are subject to the federal alternative minimum tax. If the fund were to do so, under normal circumstances, the fund may invest only up to 20% of its net assets in municipal securities that pay interest that is an item of tax preference for purposes of the alternative minimum tax.

UBS Global Asset Management (Americas) Inc. (“UBS Global AM”) acts as the fund’s investment advisor. As investment advisor, UBS Global AM makes the fund’s investment decisions. UBS Global AM selects money market instruments for the fund based on its assessment of relative values and changes in market and economic conditions.

Principal risks

All investments carry a certain amount of risk, and the fund cannot guarantee that it will achieve its investment objective. While the fund seeks to maintain the value of your investment at $1.00 per share, you may lose money by investing in the fund. An investment in the fund is not a bank deposit and is neither insured nor guaranteed by the Federal Deposit Insurance Cor- UBS Global Asset Management

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poration or any other government agency. Money market instruments generally have a low risk of loss, but they are not risk-free. The principal risks presented by an investment in the fund are:

Municipal securities risk: Municipal securities are subject to interest rate and credit risks. The ability of a municipal issuer to make payments and the value of municipal securities can be affected by uncertainties in the municipal securities market. Such uncertainties could cause increased volatility in the municipal securities market and could negatively impact the fund’s net asset value and/or the distributions paid by the fund. Municipalities continue to experience difficulties in the current economic and political environment.

Interest rate risk: The value of the fund’s investments generally will fall when short-term interest rates rise, and its yield will tend to lag behind prevailing rates. The risks associated with rising interest rates may be more pronounced going forward due to the anticipated end of an extended period of historically low rates. Market risk: The risk that the market value of the fund’s investments may fluctuate, sometimes rapidly or unpredictably, as the markets fluctuate, which may affect the fund’s ability to maintain a $1.00 share price. Market risk may affect a single issuer, industry, or sector of the economy, or it may affect the market as a whole. Moreover, changing market, economic and political conditions in one country or geographic region could adversely impact market, economic and political conditions in other countries or regions.

Liquidity risk: Although the fund invests in a diversi- fied portfolio of high quality instruments, the fund’s investments may become less liquid as a result of market developments or adverse investor perception.

Management risk: The risk that the investment strat- egies, techniques and risk analyses employed by the advisor may not produce the desired results.

Performance

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One year 0.01%

Five years 0.01

Ten years 0.93

You must be a client of UBS Financial Services Inc. or a client of certain affiliated firms to purchase fund shares. You may purchase or sell fund shares by contacting your Financial Advisor. The fund has no minimum for initial investments or to add to an account, but reserves the right to establish minimum investment requirements at any time. Shares of the fund may be purchased or redeemed through your Financial Advisor on any business day on which the Boston offices of the fund’s custodian and the New York City offices of UBS Financial Services Inc. and its bank are all open for business.

Tax information

The dividends you receive from the fund generally are not subject to federal income tax. If you are subject to alternative minimum tax, a portion of the dividends paid by the fund may be included in computing such taxes. Distributions of any capital gains are generally subject to federal income tax.

Worst quarters during years shown—3Q 2009; 1Q, 2Q & 3Q 2010; & 1Q 2011: 0.00% (Actual total returns were 0.0024%)

Updated performance information is available by contacting your Financial Advisor or by calling 1-888-793 8637 (Option #1). Calendar Year

06

0 1 4 3 5

2 6%

‘07 ‘08 ‘09

‘06

‘05 ‘10 ‘11 ‘12 ‘13 ‘14

3.09% 3.09%

1.51% 1.51% 1.85%

1.85%

2.87% 2.87%

0.01%

0.01% 0.01%0.01% 0.01%0.01% 0.01%0.01% 0.01%0.01% 0.02%

0.02% UBS RMA Tax-Free Fund Annual Total Returns

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California Municipal Money Fund

Fund summary

12

Investment objective

Maximum current income exempt from federal income tax and California personal income tax consistent with liquidity and conservation of capital.

Other expenses 0.06

Example

1 yr. 3 yrs. 5 yrs. 10 yrs.

California Municipal Money Fund $64 $202 $351 $786

The fund is a money market fund and seeks to maintain a stable price of $1.00 per share. To do this, the fund invests in a diversified portfolio of high quality money market instruments that are exempt from both federal income tax and California personal income tax. Money market instruments generally are short-term debt obligations and similar securities. They also may include longer-term bonds that have variable interest rates or other special features that give them the financial characteristics of short-term debt. Under normal circumstances, the fund will invest at least 80% of its net assets in California municipal securities. “California municipal securities” are securities issued by or on behalf of the State of California, its municipalities and public authorities and certain other issuers that pay interest that is exempt from federal income tax as well as Cali- fornia personal income tax. While the fund normally does not do so, it may invest in securities that are subject to the federal alternative minimum tax. If the fund were to do so, under normal circumstances, the fund may invest only up to 20% of its net assets in California municipal securities that pay interest that is an item of tax preference for purposes of the alternative minimum tax.

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13 Principal risks

Interest rate risk: The value of the fund’s investments generally will fall when short-term interest rates rise, and its yield will tend to lag behind prevailing rates. The risks associated with rising interest rates may be more pronounced going forward due to the anticipated end of an extended period of historically low rates. Market risk: The risk that the market value of the fund’s investments may fluctuate, sometimes rapidly or unpredictably, as the markets fluctuate, which may affect the fund’s ability to maintain a $1.00 share price. Market risk may affect a single issuer, industry, or sector of the economy, or it may affect the market as a whole. Moreover, changing market, economic and political conditions in one country or geographic region could adversely impact market, economic and political conditions in other countries or regions.

Single state concentration risk: Because the fund in- vests substantially all of its assets in California municipal money market instruments, its performance will be more severely affected by unfavorable political, fiscal or economic conditions in California than a more geo- graphically diverse fund. Although the California economy has improved since the recent recession, a

deterioration of California’s fiscal situation and the economic situation of its municipalities could cause greater volatility in the prices of California municipal money

market instruments and increase the risk of investing in the fund.

Related securities concentration risk: Because the fund may invest more than 25% of its total assets in municipal money market instruments that are issued to finance similar projects, certain economic, business or political developments or changes that affect one municipal security also may affect other municipal securities in the same sector.

Liquidity risk: Although the fund invests in a diversi- fied portfolio of high quality instruments, the fund’s investments may become less liquid as a result of market developments or adverse investor perception.

Management risk: The risk that the investment strate- gies, techniques and risk analyses employed by the advisor may not produce the desired results.

Performance

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Average annual total returns

One year 0.02%

Five years 0.01

Ten years 0.89

You must be a client of UBS Financial Services Inc. or a client of certain affiliated firms to purchase fund shares. You may purchase or sell fund shares by contacting your Financial Advisor. The fund has no minimum for initial investments or to add to an account, but reserves the right to establish minimum investment requirements at any time. Shares of the fund may be purchased or redeemed through your Financial Advisor on any business day on which the Boston offices of the fund’s custodian and the New York City offices of UBS Financial Services Inc. and its bank are all open for business.

Tax information

The dividends you receive from the fund generally are not subject to federal and California State income tax. If you are subject to alternative minimum tax, a portion of the dividends paid by the fund may be included in computing such taxes. Distributions of any capital gains are generally subject to California State income tax and federal income tax.

Worst quarters during years shown—3Q 2009; 1Q, 2Q, 3Q & 4Q 2010; & 1Q 2011: 0.00% (Actual total returns were 0.0024%)

06

0 1 4 3 5

2 6%

‘07 ‘08 ‘09

‘06

‘05 ‘10 ‘11 ‘12 ‘13 ‘14

2.96% 2.96%

1.39% 1.39% 1.76%

1.76%

2.74% 2.74%

0.01%

0.01% 0.01%0.01% 0.02%0.02% 0.01%0.01% 0.02%0.02% 0.02%

0.02%

UBS RMA California Municipal Money Fund Annual Total Returns

Calendar Year

COLORS: Black, ~note-color 2, ~note-color 3 GRAPHICS: 15587-2_Cal_Muni_Money_B.eps V1.5

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New York Municipal Money Fund

Fund summary

Maximum current income exempt from federal income tax and New York State and New York City personal income taxes consistent with liquidity and conservation of capital.

Other expenses 0.07

Example

1 yr. 3 yrs. 5 yrs. 10 yrs.

New York Municipal Money Fund $66 $208 $362 $810

The fund is a money market fund and seeks to maintain a stable price of $1.00 per share. To do this, the fund invests in a diversified portfolio of high quality money market instruments that are exempt from federal income tax and from both New York State and New York City personal income taxes.

Money market instruments generally are short-term debt obligations and similar securities. They also may include longer-term bonds that have variable interest rates or other special features that give them the financial characteristics of short-term debt. Under normal circumstances, the fund will invest at least 80% of its net assets in New York municipal securities. “New York municipal securities” are securities issued by or on behalf of the State of New York, its municipalities and public authorities and certain other issuers that pay interest that is exempt from federal income tax as well as New York State and New York City personal income taxes. While the fund normally does not do so, it may invest in securities that are subject to the federal alternative minimum tax. If the fund were to do so, under normal circumstances, the fund may invest only up to 20% of its net assets in New York municipal securities that pay interest that is an item of tax preference for purposes of the alternative minimum tax.

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16

Principal risks

Interest rate risk: The value of the fund’s investments generally will fall when short-term interest rates rise, and its yield will tend to lag behind prevailing rates. The risks associated with rising interest rates may be more pronounced going forward due to the anticipated end of an extended period of historically low rates. Market risk: The risk that the market value of the fund’s investments may fluctuate, sometimes rapidly or unpredictably, as the markets fluctuate, which may affect the fund’s ability to maintain a $1.00 share price. Market risk may affect a single issuer, industry, or sector of the economy, or it may affect the market as a whole. Moreover, changing market, economic and political conditions in one country or geographic region could adversely impact market, economic and political conditions in other countries or regions.

Single state concentration risk: Because the fund in- vests substantially all of its assets in New York municipal money market instruments, its performance will be more severely affected by unfavorable political, fiscal or economic conditions in New York than a more geo- graphically diverse fund. Although the New York economy has improved since the recent recession, a

deterioration of New York’s fiscal situation and the economic situation of its municipalities could cause greater volatility in the prices of New York municipal money

market instruments and increase the risk of investing in the fund.

Related securities concentration risk: Because the fund may invest more than 25% of its total assets in municipal money market instruments that are issued to finance similar projects, certain economic, business or political developments or changes that affect one municipal security also may affect other municipal securities in the same sector.

Liquidity risk: Although the fund invests in a diversi- fied portfolio of high quality instruments, the fund’s investments may become less liquid as a result of market developments or adverse investor perception.

Management risk: The risk that the investment strat- egies, techniques and risk analyses employed by the advisor may not produce the desired results.

Performance

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One year 0.01%

Five years 0.01

Ten years 0.89

You must be a client of UBS Financial Services Inc. or a client of certain affiliated firms to purchase fund shares. You may purchase or sell fund shares by contacting your Financial Advisor. The fund has no minimum for initial investments or to add to an account, but reserves the right to establish minimum investment requirements at any time. Shares of the fund may be purchased or redeemed through your Financial Advisor on any business day on which the Boston offices of the fund’s custodian and the New York City offices of UBS Financial Services Inc. and its bank are all open for business.

Tax information

The dividends you receive from the fund generally are not subject to federal and New York State and New York City income tax. If you are subject to alternative minimum tax, a portion of the dividends paid by the fund may be included in computing such taxes. Distri- butions of any capital gains are generally subject to New York State and New York City tax and federal income tax.

Worst quarters during years shown—3Q & 4Q 2009; 1Q, 2Q & 3Q 2010; & 1Q 2011: 0.00% (Actual total returns were 0.0024%)

06

0 1 4 3 5

2 6%

‘07 ‘08 ‘09

‘06

‘05 ‘10 ‘11 ‘12 ‘13 ‘14

2.99% 2.99%

1.39% 1.39% 1.76%

1.76%

2.75% 2.75%

0.01%

0.01% 0.01%0.01% 0.02%0.02% 0.01%0.01% 0.01%0.01% 0.01%

0.01%

UBS RMA New York Municipal Money Fund Annual Total Returns

Calendar Year

COLORS: Black, ~note-color 2, ~note-color 3 GRAPHICS: 15587-2_NY_Muni_Money_B.eps V1.5

UBS RMA Money Market Portfolio U.S. Government Portfolio Tax-Free Fund California Municipal Money Fund New York Municipal Money Fund

UBS RMA

Money Market Portfolio

U.S. Government Portfolio

Tax-Free Fund

California Municipal Money Fund

New York Municipal Money Fund

Prospectus

August 28, 2015

Contents

Money Market Portfolio

Fund summary

U.S. Government Portfolio

Fund summary

Tax-Free Fund

Fund summary

California Municipal Money Fund

Fund summary

New York Municipal Money Fund

Fund summary