UBS AG — Capital/Financing Update 2013

May 30, 2013

Filed Pursuant to Rule 424(b)(2) Registration Statement No. 333-178960

CALCULATION OF REGISTRATION FEE

Title of Each Class of Securities Offered	Maximum Aggregate Offering Price	Amount of Registration Fee(1)
Trigger Performance Securities linked to the Vanguard FTSE Emerging Markets ETF due
May 31, 2018	$3,114,520.00	$424.82

(1) Calculated in accordance with Rule 457(r) of the Securities Act of 1933.

PRICING SUPPLEMENT (To Prospectus dated January 11, 2012 and Product Supplement dated April 2, 2012)

UBS AG $3,114,520 Trigger Performance Securities

Linked to the performance of the Vanguard FTSE Emerging Markets ETF due May 31, 2018

Investment Description

UBS AG Trigger Performance Securities (the “Securities”) are unsubordinated, unsecured debt securities issued by UBS AG (“UBS”) linked to the performance of the Vanguard FTSE Emerging Markets ETF (the “underlying equity”). If the underlying return is positive, UBS will repay your principal amount at maturity plus pay a return equal to the underlying return multiplied by the participation rate of 117.52%. If the underlying return is zero or negative and the final price is equal to or greater than the trigger price, UBS will repay the full principal amount at maturity. However, if the final price is less than the trigger price, UBS will repay less than the full principal amount at maturity, if anything, resulting in a loss on your investment that is proportionate to the negative underlying return. Investing in the Securities involves significant risks. The Securities do not pay interest. You may lose some or all of your principal amount. The contingent repayment of principal only applies if you hold the Securities to maturity. Any payment on the Securities, including any repayment of principal, is subject to the creditworthiness of UBS. If UBS were to default on its payment obligations you may not receive any amounts owed to you under the Securities and you could lose your entire investment.

Features

q Participation in Positive Underlying Returns: If the underlying return is greater than zero, UBS will repay your principal amount at maturity plus pay a return equal to the underlying return multiplied by the participation rate. If the underlying return is less than zero, investors may be exposed to the negative underlying return at maturity.

q Contingent Repayment of Principal at Maturity: If the underlying return is zero or negative and the final price is not below the trigger price, UBS will repay your principal amount at maturity. However, if the final price is less than the trigger price, UBS will repay less than the full principal amount at maturity, if anything, resulting in a loss to investors that is proportionate to the negative underlying return. The contingent repayment of principal applies only if you hold the Securities to maturity. Any payment on the Securities, including any repayment of principal, is subject to the creditworthiness of UBS.

Key Dates

Trade Date	May 28, 2013
Settlement Date	May 31, 2013
Final Valuation Date*	May 25, 2018
Maturity Date*	May 31, 2018

• Subject to postponement in the event of a market disruption event, as described in the Trigger Performance Securities product supplement.

NOTICE TO INVESTORS: THE SECURITIES ARE SIGNIFICANTLY RISKIER THAN CONVENTIONAL DEBT INSTRUMENTS. THE ISSUER IS NOT NECESSARILY OBLIGATED TO REPAY THE FULL PRINCIPAL AMOUNT OF THE SECURITIES AT MATURITY, AND THE SECURITIES CAN HAVE DOWNSIDE MARKET RISK SIMILAR TO THE UNDERLYING EQUITY. THIS MARKET RISK IS IN ADDITION TO THE CREDIT RISK INHERENT IN PURCHASING A DEBT OBLIGATION OF UBS. YOU SHOULD NOT PURCHASE THE SECURITIES IF YOU DO NOT UNDERSTAND OR ARE NOT COMFORTABLE WITH THE SIGNIFICANT RISKS INVOLVED IN INVESTING IN THE SECURITIES.

YOU SHOULD CAREFULLY CONSIDER THE RISKS DESCRIBED UNDER “KEY RISKS” BEGINNING ON PAGE 5 AND UNDER “RISK FACTORS” BEGINNING ON PAGE PS-15 OF THE TRIGGER PERFORMANCE SECURITIES PRODUCT SUPPLEMENT BEFORE PURCHASING ANY SECURITIES. EVENTS RELATING TO ANY OF THOSE RISKS, OR OTHER RISKS AND UNCERTAINTIES, COULD ADVERSELY AFFECT THE MARKET VALUE OF, AND THE RETURN ON YOUR SECURITIES. YOU MAY LOSE SOME OR ALL OF YOUR INVESTMENT IN THE SECURITIES.

Security Offering

These terms relate to Trigger Performance Securities linked to the Vanguard FTSE Emerging Markets ETF. The Securities are offered at a minimum investment of $1,000, or 100 Securities at $10.00 per Security, and integral multiples of $10.00 in excess thereof.

Underlying Equity	Ticker	Participation Rate	Initial Price	Trigger Price	CUSIP	ISIN
Vanguard FTSE Emerging Markets ETF	VWO	117.52%	$43.05	$32.29, which is 75% of the Initial Price	90271C361	US90271C3613

See “Additional Information about UBS and the Securities” on page 2. The Securities will have the terms specified in the Trigger Performance Securities product supplement relating to the Securities, dated April 2, 2013, the accompanying prospectus and this pricing supplement.

Neither the Securities and Exchange Commission nor any other regulatory body has approved or disapproved of these securities or passed upon the adequacy or accuracy of this pricing supplement, the Trigger Performance Securities product supplement or the accompanying prospectus. Any representation to the contrary is a criminal offense. The Securities are not deposit liabilities of UBS AG and are not FDIC insured.

	Issue Price to Public	Underwriting Discount	Proceeds to UBS AG
Per Security	$10.00	$0.35	$9.65
Total	$3,114,520.00	$109,008.20	$3,005,511.80

UBS Financial Services Inc. Pricing Supplement dated May 28, 2013 UBS Investment Bank

Additional Information about UBS and the Securities

UBS has filed a registration statement (including a prospectus, as supplemented by a product supplement for the securities we may offer, including the Securities), with the Securities and Exchange Commission, or SEC, for the offering to which this pricing supplement relates. Before you invest, you should read these documents and any other documents relating to this offering that UBS has filed with the SEC for more complete information about UBS and this offering. You may obtain these documents without cost by visiting EDGAR on the SEC website at www.sec.gov. Our Central Index Key, or CIK, on the SEC website is 0001114446. Alternatively, UBS will arrange to send you the prospectus and the Trigger Performance Securities product supplement if you so request by calling toll-free 877-387-2275.

You may access these documents on the SEC website at www.sec.gov as follows:

¨ Product supplement for Trigger Performance Securities dated April 2, 2013:

http://www.sec.gov/Archives/edgar/data/1114446/000119312513138851/d511893d424b2.htm

¨ Prospectus dated January 11, 2012:

http://www.sec.gov/Archives/edgar/data/1114446/000119312512008669/d279364d424b3.htm

References to “UBS,” “we,” “our” and “us” refer only to UBS AG and not to its consolidated subsidiaries. In this pricing supplement, “Securities” refer to the Trigger Performance Securities that are offered hereby, unless the context otherwise requires. Also, references to the “Trigger Performance Securities product supplement” mean the UBS product supplement, dated April 2, 2013 and references to “accompanying prospectus” mean the UBS prospectus titled “Debt Securities and Warrants,” dated January 11, 2012.

This pricing supplement, together with the documents listed above, contains the terms of the Securities and supersedes all other prior or contemporaneous oral statements as well as any other written materials including pricing terms, correspondence, trade ideas, structures for implementation, sample structures, brochures or other educational materials of ours. You should carefully consider, among other things, the matters set forth in “Key Risks” beginning on page 5 and in “Risk Factors” in the accompanying product supplement, as the Securities involve risks not associated with conventional debt securities. We urge you to consult your investment, legal, tax, accounting and other advisers before deciding to invest in the Securities.

UBS reserves the right to change the terms of, or reject any offer to purchase, the Securities prior to their issuance. In the event of any changes to the terms of the Securities, UBS will notify you and you will be asked to accept such changes in connection with your purchase. You may also choose to reject such changes in which case UBS may reject your offer to purchase.

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Investor Suitability

The Securities may be suitable for you if:

¨ You fully understand the risks inherent in an investment in the Securities, including the risk of loss of your entire initial investment.

¨ You can tolerate a loss of all or a substantial portion of your investment and are willing to make an investment that may have the same downside market risk as the underlying equity.

¨ You believe the underlying equity will appreciate over the term of the Securities.

¨ You are willing to invest in the Securities based on the participation rate indicated on the first page of this pricing supplement.

¨ You can tolerate fluctuations in the price of the Securities prior to maturity that may be similar to or exceed the downside fluctuations in the price of the underlying equity.

¨ You do not seek current income from your investment and are willing to forgo any dividends paid on the underlying equity.

¨ You are willing to hold the Securities to maturity, a term of approximately 5 years, and accept that there may be little or no secondary market for the Securities.

¨ You are willing to assume the credit risk of UBS for all payments under the Securities, and understand that if UBS defaults on its obligations you may not receive any amounts due to you including any repayment of principal.

The Securities may not be suitable for you if:

¨ You do not fully understand the risks inherent in an investment in the Securities, including the risk of loss of your entire initial investment.

¨ You require an investment designed to provide a full return of principal at maturity.

¨ You cannot tolerate a loss of all or a substantial portion of your investment and are unwilling to make an investment that may have the same downside market risk as the underlying equity.

¨ You believe that the price of the underlying equity will decline during the term of the Securities and is likely to close below the trigger price on the final valuation date.

¨ You are unwilling to invest in the Securities based on the participation rate indicated on the first page of this pricing supplement.

¨ You cannot tolerate fluctuations in the price of the Securities prior to maturity that may be similar to or exceed the downside fluctuations in the price of the underlying equity.

¨ You seek current income from this investment or prefer to receive the dividends paid on the underlying equity.

¨ You are unable or unwilling to hold the Securities to maturity, a term of approximately 5 years, or you seek an investment for which there will be an active secondary market.

¨ You are not willing to assume the credit risk of UBS for all payments under the Securities.

The investor suitability considerations identified above are not exhaustive. Whether or not the Securities are a suitable investment for you will depend on your individual circumstances and you should reach an investment decision only after you and your investment, legal, tax, accounting and other advisors have carefully considered the suitability of an investment in the Securities in light of your particular circumstances. You should also review “Key Risks” beginning on page 5 of this pricing supplement and the more detailed “Risk Factors” beginning on PS-15 of the Trigger Performance Securities product supplement for risks related to an investment in the Securities.

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Final Terms

Issuer	UBS AG, London Branch
Principal Amount	$10.00 per Security (subject to a minimum investment of 100 Securities)
Term	Approximately 5 years.
Underlying Equity	Vanguard FTSE Emerging Markets ETF
Participation Rate	117.52%
Payment at Maturity (per Security)	If the underlying return is positive , UBS will pay you an amount in cash equal to: $10 + ($10 × Underlying Return × Participation Rate) If the underlying return is zero or negative and the final price is equal to or greater than
the trigger price , UBS will pay you an amount in cash equal to your principal amount, or $10 per Security. If the final price is less than the trigger price, UBS will pay you an amount that is less than your principal amount, if anything, resulting in a loss on your investment that is proportionate to the
negative underlying return: $10 + ($10 ×
Underlying Return)
Underlying Return	Final Price – Initial Price Initial Price
Initial Price	$43.05, which is the closing price of the underlying equity on the trade date.
Final Price	The closing price of the underlying equity on the final valuation date.
Trigger Price	$32.29, which is 75% of the initial price.

Investment Timeline

Trade Date	The initial price is observed. The participation rate is set.
●
Maturity
Date	The final price is observed on the final valuation date and the underlying return is calculated. If the underlying return is positive , UBS will pay you a cash payment at maturity equal
to: $10 + ($10 × Underlying Return × Participation Rate) If the underlying return is zero or negative and the final price is equal to or greater than the trigger price , UBS will pay you a cash payment equal to your
principal amount, or $10 per Security. If the underlying return is negative and
the final price is less than the trigger price , UBS will pay you a cash payment at maturity that is less than your principal amount, if anything, equal to: $10 + ($10 × Underlying Return). In such scenario, you will suffer a loss on your initial investment in an amount that is proportionate to the negative underlying return.

INVESTING IN THE SECURITIES INVOLVES SIGNIFICANT RISKS. YOU MAY LOSE SOME OR ALL OF YOUR PRINCIPAL AMOUNT. ANY PAYMENT ON THE SECURITIES, INCLUDING ANY REPAYMENT OF PRINCIPAL, IS SUBJECT TO THE CREDITWORTHINESS OF UBS. IF UBS WERE TO DEFAULT ON ITS PAYMENT OBLIGATIONS, YOU MAY NOT RECEIVE ANY AMOUNTS OWED TO YOU UNDER THE SECURITIES AND YOU COULD LOSE YOUR ENTIRE INVESTMENT.

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Key Risks

An investment in the Securities involves significant risks. Some of the risks that apply to the Securities are summarized here, but we urge you to read the more detailed explanation of risks relating to the Securities generally in the “Risk Factors” section of the Trigger Performance Securities product supplement. We also urge you to consult your investment, legal, tax, accounting and other advisers before you invest in the Securities.

¨ Risk of loss — The Securities differ from ordinary debt securities in that the issuer will not necessarily repay the full principal amount of the Securities. If the underlying return is negative, UBS will repay you the principal amount of your Securities in cash only if the final price is greater than or equal to the trigger price and will only make such payment at maturity. If the final price is below the trigger price, you will lose some or all of your initial investment in an amount proportionate to the decline in the price of the underlying equity from the trade date to the final valuation date.

¨ The contingent repayment of principal applies only at maturity — You should be willing to hold your Securities to maturity. If you are able to sell your Securities prior to maturity in the secondary market, you may have to sell them at a loss relative to your initial investment even if the price of the underlying equity is above the trigger price.

¨ The participation rate applies only at maturity — You should be willing to hold your Securities to maturity. If you are able to sell your Securities prior to maturity in the secondary market, the price you receive will likely not reflect the full economic value of the participation rate or the Securities themselves and the return you realize may be less than the underlying return even if such return is positive. You can receive the full benefit of the participation rate only if you hold your Securities to maturity.

¨ No interest payments — UBS will not pay any interest with respect to the Securities.

¨ Credit risk of UBS — The Securities are unsubordinated and unsecured debt obligations of the issuer, UBS and are not, either directly or indirectly, an obligation of any third party. Any payment to be made on the Securities, including any repayment of principal, depends on the ability of UBS to satisfy its obligations as they come due. As a result, the actual and perceived creditworthiness of UBS may affect the market value of the Securities and, in the event UBS were to default on its obligations, you may not receive any amounts owed to you under the terms of the Securities and you could lose your entire initial investment.

¨ Market risk — The price of the underlying equity can rise or fall sharply due to factors specific to that underlying equity or the securities constituting the assets of the underlying equity. These factors may include price volatility, earnings, financial conditions, corporate, industry and regulatory developments, management changes and decisions and other events, as well as general market factors, such as general market volatility and levels, interest rates and economic and political conditions. We urge you to review financial and other information filed periodically by the underlying equity with the SEC.

¨ Owning the Securities is not the same as owning the underlying equity — The return on your Securities is unlikely to reflect the return you would realize if you actually owned the underlying equity or the stocks included in the underlying equity. For instance, you will not receive or be entitled to receive any dividend payments or other distributions on the underlying equity or the stocks included in the underlying equity during the term of your Securities. As an owner of the Securities, you will not have voting rights or any other rights that holders of the underlying equity or stocks included in the underlying equity may have.

¨ No assurance that the investment view implicit in the Securities will be successful — It is impossible to predict whether the price of the underlying equity will rise or fall. The closing price of the underlying equity will be influenced by complex and interrelated political, economic, financial and other factors that affect the underlying equity. You should be willing to accept the downside risks of owning equities in general and the underlying equity in particular, and to assume the risk that, you may lose some or all of your initial investment.

¨ There is no affiliation between UBS and the issuers of the constituent stocks of the underlying equity (the “underlying equity constituent stock issuers”), and UBS is not responsible for any disclosure by such issuers — We are not affiliated with the underlying equity constituent stock issuers. However, we and our affiliates may currently or from time to time in the future engage in business with the underlying equity constituent stock issuers. We do not disclaim liability or responsibility for any information disclosed herein regarding the underlying equity. However, UBS has not conducted any independent review or due diligence of any publicly available information with respect to the underlying equity. You, as an investor in the Securities, should make your own investigation into the underlying equity and the underlying equity constituent stock issuers. The underlying equity constituent stock issuers are not involved in the Securities offered hereby in any way and have no obligation of any sort with respect to your Securities. The underlying equity constituent stock issuers have no obligation to take your interests into consideration for any reason, including when taking any corporate actions that might affect the value of your Securities.

¨ The calculation agent can make adjustments that affect the payment to you at maturity — For certain corporate events affecting the underlying equity, the calculation agent may make adjustments to the initial price or trigger price. However, the calculation agent will not make an adjustment in response to all events that could affect the underlying equity. If an event occurs that does not require the calculation agent to make an adjustment, the value of the Securities may be materially and adversely affected. In addition, all determinations and calculations concerning any such adjustments will be made by the calculation agent. You should be aware that the

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calculation agent may make any such adjustment, determination or calculation in a manner that differs from that discussed in the product supplement as necessary to achieve an equitable result. Following a delisting or discontinuance of the underlying equity, the amount you receive at maturity may be based on a share of another exchange traded fund. The occurrence of these events and the consequent adjustments may materially and adversely affect the value of the Securities. For more information, see the section “General Terms of the Securities — Antidilution Adjustments” and “General Terms of the Securities — Delisting, Discontinuance or Modification of an ETF” in the product supplement. Regardless of any of the events discussed above, any payment on the Securities is subject to the creditworthiness of UBS.

¨ The value of the underlying equity may not completely track the value of the securities in which the underlying equity invests — Although the trading characteristics and valuations of the underlying equity will usually mirror the characteristics and valuations of the securities in which the underlying equity invests, its value may not completely track the value of the securities in which the underlying equity invests. The value of the underlying equity will reflect transaction costs and fees that the securities in which the underlying equity invests do not have. In addition, although the underlying equity may be currently listed for trading on an exchange, there is no assurance that an active trading market will continue for the underlying equity or that there will be liquidity in the trading market.

¨ Fluctuation of NAV — The net asset value (the “NAV”) of an exchange traded fund may fluctuate with changes in the market value of such exchange traded fund’s securities holdings. The market prices of the underlying equity may fluctuate in accordance with changes in NAV and supply and demand on the applicable stock exchanges. In addition, the market price of the underlying equity may differ from its NAV per share; the underlying equity may trade at, above or below their NAV per share.

¨ Failure of the underlying equity to track the level of the underlying index — While the underlying equity is designed and intended to track the level of a specific index (an “underlying index”), various factors, including fees and other transaction costs, will prevent the underlying equity from correlating exactly with changes in the level of such underlying index. Accordingly, the performance of the underlying equity will not be equal to the performance of its underlying index during the term of the Securities.

¨ The underlying equity’s underlying index is currently in a process of transition to a new underlying index, which could reduce the underlying return, and limit the utility of available information about the performance of the underlying equity — Until 2013, the underlying index was the MSCI Emerging Markets Index (the “MXEA”). In January 2013, The Vanguard Group, Inc. (“Vanguard”) announced that the underlying equity is expected to adopt the FTSE Emerging Index as its new target index over the coming months. In the first phase of the transition, which began on January 10, 2013, the underlying equity ceased tracking the MXEA, and began temporarily tracking the FTSE Emerging Transition Index, a “dynamic” index that is gradually reducing its exposure to South Korean equities by approximately 4% each week for a period of 25 weeks, while proportionately adding exposure to stocks of companies located in other countries based on their weightings in the new index. In the second phase of the transition, the underlying equity will cease tracking the FTSE Emerging Transition Index and begin tracking the FTSE Emerging Index.

¨ There may be little or no secondary market — The Securities will not be listed or displayed on any securities exchange or any electronic communications network. There can be no assurance that a secondary market for the Securities will develop. UBS Securities LLC and other affiliates of UBS may make a market in the offering of the Securities, although they are not required to do so and may stop making a market at any time. If you are able to sell your Securities prior to maturity, you may have to sell them at a substantial loss.

¨ The Securities are subject to currency exchange rate risk — The Vanguard FTSE Emerging Markets ETF (“VWO Fund”) invests in securities that are traded and quoted in foreign currencies on non-U.S. markets. Therefore, holders of the Securities will be exposed to currency exchange rate risk with respect to the currencies in which such securities trade. The values of the currencies of the countries in which the VWO Fund may invest may be subject to a high degree of fluctuation due to changes in interest rates, the effects of monetary policies issued by the United States, foreign governments, central banks or supranational entities, the imposition of currency controls or other national or global political or economic developments. An investor’s net exposure will depend on the extent to which the relevant non-U.S. currencies strengthen or weaken against the U.S. dollar and the relative weight of each non-U.S. security in the portfolio of VWO Fund. If, taking into account such weighting, the U.S. dollar strengthens against the relevant non-U.S. currencies, the value of securities in which the VWO Fund invests will be adversely affected and the value of the Securities may decrease.

¨ The Securities are subject to non-U.S. securities market risk — The Securities are linked to shares of the VWO Fund and therefore, are subject to risks associated with non-U.S. securities markets. An investment in securities linked directly or indirectly to the value of securities issued by non-U.S. companies involves particular risks. Generally, non-U.S. securities markets may be more volatile than U.S. securities markets, and market developments may affect non-U.S. markets differently from U.S. securities markets. Direct or indirect government intervention to stabilize these non-U.S. markets, as well as cross shareholdings in non-U.S. companies, may affect trading prices and volumes in those markets. There is generally less publicly available information about non-U.S. companies than about those U.S. companies that are subject to the reporting requirements of the SEC, and non-U.S. companies are subject to accounting, auditing and financial reporting standards and requirements that differ from those applicable to U.S. reporting companies. Securities prices in non-U.S. countries are subject to political, economic, financial and social factors that may be unique to the particular country. These factors, which could negatively affect the non-U.S. securities markets, include the possibility of recent or future changes in the non-U.S. government’s economic and fiscal policies, the possible imposition of, or changes in, currency exchange laws or other non-U.S. laws or restrictions applicable to non-U.S. companies or investments in non-U.S. equity securities and the possibility of fluctuations in the rate of exchange between currencies. Moreover, certain aspects of a particular non-U.S. economy may differ favorably or unfavorably from the U.S. economy in important respects, such as growth of gross national product, rate of inflation, capital reinvestment, resources and self-sufficiency. Finally, it will likely be more costly and difficult to enforce the laws or regulations of a non-U.S. country or exchange.

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¨ The Securities are subject to emerging markets risk — The Securities are linked to shares of the VWO Fund and therefore, are subject to emerging markets risk. Investments in securities linked directly or indirectly to emerging market equity securities involve many risks, including, but not limited to: economic, social, political, financial and military conditions in the emerging market; regulation by national, provincial, and local governments; less liquidity and smaller market capitalizations than exist in the case of many large U.S. companies; different accounting and disclosure standards; and political uncertainties. Securities of emerging market companies may be more volatile and may be affected by market developments differently than U.S. companies. Government interventions to stabilize securities markets and cross-shareholdings may affect prices and volume of trading of the securities of emerging market companies. Economic, social, political, financial and military factors could, in turn, negatively affect such companies’ value. These factors could include changes in the emerging market government’s economic and fiscal policies, possible imposition of, or changes in, currency exchange laws or other laws or restrictions applicable to the emerging market companies or investments in their securities, and the possibility of fluctuations in the rate of exchange between currencies. Moreover, emerging market economies may differ favorably or unfavorably from the U.S. economy in a variety of ways, including growth of gross national product, rate of inflation, capital reinvestment, resources and self-sufficiency. You should carefully consider the risks related to emerging markets, to which the Securities are susceptible, before making a decision to invest in the Securities.

¨ Price of Securities prior to maturity — The market price of the Securities will be influenced by many unpredictable and interrelated factors, including the price of the underlying equity; the volatility of the underlying equity; the dividend rate paid on the underlying equity; the time remaining to the maturity of the Securities; interest rates in the markets; geopolitical conditions and economic, financial, political and regulatory or judicial events; and the creditworthiness of UBS.

¨ Impact of fees on secondary market prices — Generally, the price of the Securities in the secondary market is likely to be lower than the initial price since the issue price included, and the secondary market prices are likely to exclude, commissions, hedging costs or other compensation paid with respect to the Securities.

¨ Potential UBS impact on price — Trading or transactions by UBS or its affiliates in the underlying equity, the stocks included in the underlying equity and/or over-the-counter options, futures or other instruments with returns linked to the performance of the underlying equity or stocks included in the underlying equity may adversely affect the performance and, therefore, the market value of the Securities.

¨ Potential conflict of interest — UBS and its affiliates may engage in business with the issuer of the underlying equity, which may present a conflict between the obligations of UBS and you, as a holder of the Securities. There are also potential conflicts of interest between you and the calculation agent, which will be an affiliate of UBS.

¨ Potentially inconsistent research, opinions or recommendations by UBS — UBS and its affiliates publish research from time to time on financial markets and other matters that may influence the value of the Securities, or express opinions or provide recommendations that are inconsistent with purchasing or holding the Securities. Any research, opinions or recommendations expressed by UBS or its affiliates may not be consistent with each other and may be modified from time to time without notice. Investors should make their own independent investigation of the merits of investing in the Securities and the underlying equity to which the Securities are linked.

¨ Dealer incentives — UBS and its affiliates act in various capacities with respect to the Securities. We and our affiliates may act as a principal, agent or dealer in connection with the sale of the Securities. Such affiliates, including the sales representatives, will derive compensation from the distribution of the Securities and such compensation may serve as an incentive to sell these Securities instead of other investments. We will pay total underwriting compensation of $0.35 per Security to any of our affiliates acting as agents or dealers in connection with the distribution of the Securities.

¨ Uncertain tax treatment — Significant aspects of the tax treatment of the Securities are uncertain. You should consult your own tax advisor about your tax situation.

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Hypothetical Examples and Return Table of the Securities at Maturity

The examples and table below illustrate the Payment at Maturity for a $10.00 Security on a hypothetical offering of the Securities, with the following assumptions:

Term:	Approximately 5 years
Initial Price:	$43.05
Trigger Price:	$32.29 (75% of Initial Price)
Participation Rate:	117.52%
Range of Underlying return:	-100% to 100%

The examples are provided for illustrative purposes only and are purely hypothetical. The numbers in the examples and in the table below have been rounded for ease of analysis.

Example 1: The underlying return is 20%.

Since the underlying return is positive, the payment at maturity per Security will be calculated as follows:

$10 + ($10 × 20% × 117.52%) = $12.35 per Security (a 23.50% return).

Example 2: The underlying return is -20% and the final price is above the trigger price.

Since the underlying return is negative but the final price is above the trigger price of $32.29, UBS will repay the full principal amount and the payment at maturity is equal to $10.00 per Security (a zero percent return).

Example 3: The underlying return is -60%, making the final price below the trigger price.

Since the underlying return is negative and the final price is below the trigger price, UBS will pay you less than the full principal amount of your Securities and your investment in the Securities will be fully exposed to the decline of the underlying equity. In this example, the payment at maturity is calculated as follows:

$10 + ($10 × -60%) = $10 – $6 = $4 per Security (a 60% loss).

If the underlying equity closes below the trigger price on the final valuation date, your investment in the Securities is fully exposed to the decline of the underlying equity and you will lose some or all of your principal at maturity.

| Underlying Equity — Final Price | Underlying
Return (1) | Payment and Return at Maturity — Payment at Maturity | Security Total Return at Maturity |
| --- | --- | --- | --- |
| $86.10 | 100.00% | $21.75 | 117.52% |
| $81.80 | 90.00% | $20.58 | 105.77% |
| $77.49 | 80.00% | $19.40 | 94.02% |
| $73.19 | 70.00% | $18.23 | 82.26% |
| $68.88 | 60.00% | $17.05 | 70.51% |
| $64.58 | 50.00% | $15.88 | 58.76% |
| $60.27 | 40.00% | $14.70 | 47.01% |
| $55.97 | 30.00% | $13.53 | 35.26% |
| $51.66 | 20.00% | $12.35 | 23.50% |
| $47.36 | 10.00% | $11.18 | 11.75% |
| $43.05 | 0.00% | $10.00 | 0.00% |
| $38.75 | -10.00% | $10.00 | 0.00% |
| $34.44 | -20.00% | $10.00 | 0.00% |
| $32.29 | -25.00% | $10.00 | 0.00% |
| $25.83 | -40.00% | $6.00 | -40.00% |
| $21.53 | -50.00% | $5.00 | -50.00% |
| $17.22 | -60.00% | $4.00 | -60.00% |
| $12.92 | -70.00% | $3.00 | -70.00% |
| $8.61 | -80.00% | $2.00 | -80.00% |
| $4.31 | -90.00% | $1.00 | -90.00% |

(1) The underlying return excludes any cash dividend payments.

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What Are the Tax Consequences of the Securities?

The United States federal income tax consequences of your investment in the Securities are uncertain. Some of these tax consequences are summarized below, but we urge you to read the more detailed discussion in “Supplemental U.S. Tax Considerations” beginning on page PS-44 of the Trigger Performance Securities product supplement and discuss the tax consequences of your particular situation with your tax advisor.

There are no statutory provisions, regulations, published rulings or judicial decisions addressing the characterization for U.S. federal income tax purposes of securities with terms that are substantially the same as the Securities. Pursuant to the terms of the Securities, UBS and you agree, in the absence of a statutory, regulatory, administrative or judicial ruling to the contrary, to characterize your Securities as a pre-paid derivative contract with respect to the underlying assets. If your Securities are so treated, you should generally recognize gain or loss upon the sale or maturity of your Securities. Subject to the “constructive ownership” rules, discussed below, any gain or loss recognized upon sale, exchange or settlement of the Securities should be long-term if you hold your Securities for more than one year, in an amount equal to the difference between the amount you receive at such time and the amount you paid for your Securities, and short-term capital gain or loss otherwise.

Since the Securities are linked to an equity interest in an exchange traded fund, there is a risk that the Securities would be treated as a “constructive ownership transaction” as defined in Section 1260 of the Internal Revenue Code of 1986, as amended (the “Code”). A “constructive ownership transaction” includes certain contracts under which an investor will receive payment equal to or credit for the future value of any equity interest in a regulated investment company (such as the underlying equity). If an investment in Securities is treated as a “constructive ownership transaction,” any long-term capital gain recognized by a United States holder (as defined under “Supplemental U.S. Tax Consideration” on page PS-44 of the Relative Performance Securities product supplement) in respect of a Security will be recharacterized as ordinary income to the extent such gain exceeds the amount of “net underlying long-term capital gain” (as defined in Section 1260 of the Code) of the United States holder (the “Excess Gain”). It is not clear how the “net underlying long-term capital gain” would be computed in respect of a Security. It is possible, for example, that the “net underlying long-term capital gain” could equal the amount of long-term capital gain a United States holder would have recognized if on the issue date of the Security the holder had invested the face amount of the Security in shares of the underlying equity and sold those shares for their fair market value on the date the Security is sold, exchanged or retired. Unless otherwise established by clear and convincing evidence, the “net underlying long-term capital gain” is treated as zero. In addition, an interest charge will also apply to any deemed underpayment of tax in respect of any Excess Gain to the extent such gain would have resulted in gross income inclusion for the United States holder in taxable years prior to the taxable year of the sale, exchange or maturity of the Security (assuming such income accrued such that the amount in each successive year is equal to the income in the prior year increased at a constant rate equal to the applicable federal rate as of the date of sale, exchange or maturity of the Security).

Accordingly, all or a portion of any gain on the sale or settlement of a Security after one year could be treated as “Excess Gain” from a “constructive ownership transaction,” which gain would be recharacterized as ordinary income, and subject to an interest charge. U.S. holders should consult their tax advisors regarding the potential application of the “constructive ownership” rules.

In the opinion of our counsel, Cadwalader, Wickersham & Taft LLP, it would be reasonable to treat your Securities in the manner described above. However, because there is no authority that specifically addresses the tax treatment of the Securities, it is possible that your Securities could alternatively be treated for tax purposes in the manner described under “Supplemental U.S. Tax Considerations — Alternative Treatments” on page PS-46 of the product supplement, and that the timing and character of income or loss on your Securities could be materially and adversely affected.

The Internal Revenue Service, for example, might assert that you should be required to recognize taxable gain on any rebalancing or rollover of the underlying equity.

In 2007, the Internal Revenue Service released a notice that may affect the taxation of holders of the Securities. According to the notice, the Internal Revenue Service and the Treasury Department are actively considering whether the holder of an instrument similar to the Securities should be required to accrue ordinary income on a current basis, and they are seeking taxpayer comments on the subject. It is not possible to determine what guidance they will ultimately issue, if any. It is possible, however, that under such guidance, holders of the Securities will ultimately be required to accrue income currently and this could be applied on a retroactive basis. The Internal Revenue Service and the Treasury Department are also considering other relevant issues, including whether additional gain or loss from such instruments should be treated as ordinary or capital, whether foreign holders of such instruments should be subject to withholding tax on any deemed income accruals, and whether the special “constructive ownership rules” of Section 1260 of the Internal Revenue Code of 1986, as amended (the “Code”) should be applied to such instruments. Holders are urged to consult their tax advisors concerning the significance, and the potential impact, of the above considerations. Except to the extent otherwise required by law, UBS intends to treat your Securities for United States federal income tax purposes in accordance with the treatment described above and under “Supplemental U.S. Tax Considerations” beginning on page PS-44 of the Trigger Performance Securities product supplement, unless and until such time as the Treasury Department and the Internal Revenue Service determine that some other treatment is more appropriate.

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Medicare Tax on Net Investment Income. Beginning in 2013, U.S. holders that are individuals, estates, and certain trusts will be subject to an additional 3.8% tax on all or a portion of their “net investment income,” which may include any gain realized with respect to the Securities, to the extent of their net investment income that when added to their other modified adjusted gross income, exceeds $200,000 for an unmarried individual, $250,000 for a married taxpayer filing a joint return (or a surviving spouse), or $125,000 for a married individual filing a separate return. U.S. holders should consult their tax advisors with respect to their consequences with respect to the 3.8% Medicare tax.

Specified Foreign Financial Assets. Under recently enacted legislation, individuals that own “specified foreign financial assets” may be required to file information with respect to such assets with their tax returns, especially if such assets are held outside the custody of a U.S. financial institution. You are urged to consult your tax adviser as to the application of this legislation to your ownership of the Securities.

Non-U.S. Holders. Subject to Section 871(m) and FATCA (as discussed below), if you are not a United States holder, you should generally not be subject to United States withholding tax with respect to payments on your Securities or to generally applicable information reporting and backup withholding requirements with respect to payments on your Securities if you comply with certain certification and identification requirements as to your foreign status (by providing a fully completed and duly executed appropriate Internal Revenue Service (“IRS”) Form W-8). Gain from the sale or exchange of a Security or settlement at maturity generally will not be subject to U.S. tax unless such gain is effectively connected with a trade or business conducted by the non-U.S. holder in the United States or unless the non-U.S. holder is a non-resident alien individual and is present in the U.S. for 183 days or more during the taxable year of such sale, exchange or settlement and certain other conditions are satisfied.

Section 871(m) of the Code requires withholding (up to 30%, depending on the applicable treaty) on certain financial instruments to the extent that the payments or deemed payments on the financial instruments are contingent upon or determined by reference to U.S.-source dividends. Under proposed U.S. Treasury Department regulations, certain payments that are contingent upon or determined by reference to U.S. source dividends, including payments reflecting adjustments for extraordinary dividends, with respect to equity-linked instruments, including the Securities, may be treated as dividend equivalents. If enacted in their current form, the regulations may impose a withholding tax on payments made on the Securities on or after January 1, 2014 that are treated as dividend equivalents. In that case, we (or the applicable paying agent) would be entitled to withhold taxes without being required to pay any additional amounts with respect to amounts so withheld. Further, Non-U.S. Holders may be required to provide certifications prior to, or upon the sale, redemption or maturity of the Securities in order to minimize or avoid U.S. withholding taxes.

Foreign Account Tax Compliance Act. The Foreign Account Tax Compliance Act (“FATCA”) was enacted on March 18, 2010, and imposes a 30% U.S. withholding tax on “withholdable payments” (i.e., certain U.S. source payments, including interest (and OID), dividends, other fixed or determinable annual or periodical gain, profits, and income, and on the gross proceeds from a disposition of property of a type which can produce U.S. source interest of dividends) and “pass-thru payments” (i.e, certain payments attributable to withholdable payments) made to certain foreign financial institutions (and certain of their affiliates) unless the payee foreign financial institution agrees, among other things, to disclose the identity of any U.S. individual with an account of the institution (or the relevant affiliate) and to annually report certain information about such account. FATCA also requires withholding agents making withholdable payments to certain foreign entities that do not disclose the name, address, and taxpayer identification number of any substantial U.S. owners (or certify that they do not have any substantial United States owners) withhold tax at a rate of 30%. Under certain circumstances, a holder may be eligible for refunds or credits of such taxes.

Pursuant to final Treasury regulations published in the Federal Register on January 28, 2013, the withholding and reporting requirements will generally apply to certain withholdable payments made after December 31, 2013, certain gross proceeds on sale or disposition occurring after December 31, 2016, and certain pass-thru payments made after December 31, 2016. This withholding tax would not be imposed on withholdable payments pursuant to obligations that are outstanding on January 1, 2014 (and are not materially modified after December 31, 2013) or to pass-thru payments pursuant to obligations that are outstanding six months after final regulations regarding such payments become effective (and such obligations are not subsequently modified in a material manner). If, however, withholding is required as a result of future guidance, we (and any paying agent) will not be required to pay additional amounts with respect to the amounts so withheld.

Significant aspects of the application of FATCA are not currently clear and the above description is based on regulations and interim guidance. Investors should consult their own advisor about the application of FATCA, in particular if they may be classified as financial institutions under the FATCA rules.

Proposed Legislation

The House Ways and Means Committee has released in draft form certain proposed legislation relating to financial instruments. If enacted, the effect of this legislation generally would be to require instruments such as the Securities to be marked to market on as annual basis with the all gains and losses to be treated as ordinary, subject to certain exceptions. You are urged to consult your tax advisor regarding the draft legislation and its possible impact on you.

PROSPECTIVE PURCHASERS OF SECURITIES SHOULD CONSULT THEIR TAX ADVISORS AS TO THE U.S. FEDERAL, STATE, LOCAL AND OTHER TAX CONSEQUENCES TO THEM OF THE PURCHASE, OWNERSHIP AND DISPOSITION OF THE SECURITIES.

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Vanguard FTSE Emerging Markets ETF

We have derived all information contained herein regarding the Vanguard FTSE Emerging Markets ETF (the “VWO Fund”) from publicly available information. Such information reflects the policies of, and is subject to change by The Vanguard Group, Inc. (“Vanguard”), the investment adviser of the VWO Fund. UBS has not undertaken an independent review or due diligence of any publicly available information regarding the VWO Fund.

VWO Fund is an exchange-traded class of shares issued by the Vanguard Emerging Markets Stock Index Fund and is maintained and managed by Vanguard. Vanguard is a mutual fund and is jointly owned by the funds it oversees and thus, indirectly by the shareholders in those funds. The Vanguard Trust is a registered investment company that consists of separate funds, each of which may consist of different share classes, including ETF shares. The VWO Fund currently tracks the performance of the FTSE Emerging Transition Index (the “Transition Index”), which is expected to operate until July 2013. Subsequently, the VWO Fund will track the performance of the FTSE Emerging Index (the “Underlying Index”). Both the Transition Index and the Underlying Index were developed by FTSE International Limited (“FTSE”) and are calculated, maintained and published by FTSE International Limited (“FTSE”).

Historically, the VWO Fund sought to track the performance of the MSCI Emerging Markets Index. Starting in January of 2013, the VWO Fund began a two-step transition process to instead track the performance of the Underlying Index. First, in January 2013, the VWO Fund began tracking the performance of the Transition Index. Second, in July 2013, Vanguard expects that the VWO Fund will begin to track the Underlying Index. The Transition Index was created to provide Vanguard with the ability to transition existing emerging markets funds to the Underlying Index over a period of approximately six months in a manner designed to reduce the impact on its existing fund shareholders.

The Transition Index is a “dynamic” index that represents the components of the Underlying Index plus South Korean equity exposure. The Transition Index will gradually reduce South Korean equity exposure by approximately 4% each week over a period of 25 weeks while proportionately adding exposure to stocks of companies located in other countries based on their weightings in the Underlying Index. The Underlying Index includes common stocks of companies located in emerging markets around the world.

As of December 31, 2012, the net expense ratio of the VWO Fund is expected to accrue at an annual rate of 0.20% of the VWO Fund’s daily net asset value. Expenses of the VWO Fund reduce the net value of the assets held by the VWO Fund and, therefore, reduce value of the shares of the VWO Fund.

As of December 31, 2012, the VWO Fund’s five largest company holdings include: Samsung Electronics Co. Ltd. (4.10%), Taiwan Semiconductor Manufacturing Co. Ltd. (2.10%), China Mobile Ltd (1.80%), Petroleo Brasileiro SA (1.80%) and Vale SA (1.70%). As of December 31, 2012, the VWO Fund’s five largest countries as a percentage of common stock were China, Korea, Brazil, Taiwan and South Africa.

Information filed by Vanguard International Equity Index Funds with the SEC under the Securities Act of 1933 and the Investment Company Act of 1940 can be found by reference to its SEC file number: 033-32548 and 81105972. The VWO Fund’s website is https://institutional.vanguard.com/VGApp/iip/site/institutional/investments/productoverview?fundId=0964. Shares of the VWO Fund are listed on the NYSE Arca under ticker symbol “VWO.”

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Historical Information

The following table sets forth the quarterly high and low closing price for the Vanguard FTSE Emerging Markets ETF, based on the daily closing price as reported by Bloomberg Professional ® Service (“Bloomberg”), without independent verification. UBS has not conducted any independent review or due diligence of publicly available information obtained from Bloomberg. The closing price of the Vanguard FTSE Emerging Markets ETF on May 28, 2013 was $43.05. Prior to January 2013, the performance of the underlying equity resulted from its tracking of the MSCI Emerging Markets Index. Therefore, the underlying equity’s historical pricing may be of limited value in assessing its performance. Past performance of the underlying equity is not indicative of the future performance of the underlying equity .

Quarter Begin	Quarter End	Quarterly High	Quarterly Low	Quarterly Close
1/2/2009	3/31/2009	$25.68	$19.04	$23.60
4/1/2009	6/30/2009	$33.89	$24.39	$31.82
7/1/2009	9/30/2009	$39.01	$30.57	$38.56
10/1/2009	12/31/2009	$41.71	$37.54	$41.00
1/4/2010	3/31/2010	$42.80	$36.85	$42.18
4/1/2010	6/30/2010	$43.98	$36.38	$37.99
7/1/2010	9/30/2010	$45.40	$38.22	$45.40
10/1/2010	12/31/2010	$49.32	$45.54	$48.15
1/3/2011	3/31/2011	$48.92	$45.00	$48.92
4/1/2011	6/30/2011	$50.71	$46.44	$48.62
7/1/2011	9/30/2011	$49.52	$35.89	$35.89
10/3/2011	12/30/2011	$43.47	$35.20	$38.21
1/3/2012	3/30/2012	$45.09	$38.57	$43.47
4/2/2012	6/29/2012	$43.99	$37.08	$39.95
7/2/2012	9/28/2012	$43.25	$38.28	$41.75
10/1/2012	12/31/2012	$44.53	$40.44	$44.53
1/2/2013	3/28/2013	$45.45	$42.24	$42.89
4/1/2013*	5/28/2013*	$44.79	$41.23	$43.05

• As of the date of this pricing supplement, available information for the second calendar quarter of 2013 includes data for the period from April 1, 2013 through May 28, 2013. Accordingly, the “Quarterly High,” “Quarterly Low” and “Quarterly Close” data indicated are for this shortened period only and do not reflect complete data for the second calendar quarter of 2013.

The graph below illustrates the performance of the underlying equity from January 3, 2005 through May 28, 2013, (which includes its tracking of the MSCI Emerging Markets Index and the FTSE Emerging Transition Index) based on information from Bloomberg. The dotted line represents the trigger price of $32.29, which is equal to 75% of the closing price of the underlying equity on May 28, 2013. Past performance of the underlying equity is not indicative of the future performance of the underlying equity .

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Supplemental Plan of Distribution (Conflicts of Interest)

We have agreed to sell to UBS Financial Services Inc. and certain of its affiliates, together the “Agents,” and the Agents have agreed to purchase, all of the Securities at the issue price less the underwriting discount indicated on the cover of this pricing supplement, the document filed pursuant to Rule 424(b) containing the final pricing terms of the Securities.

We or one of our affiliates may enter into swap agreements or related hedge transactions with one of our other affiliates or unaffiliated counterparties in connection with the sale of the Securities and UBS or its affiliates may earn additional income as a result of payments pursuant to the swap or related hedge transactions.

Conflicts of Interest — Each of UBS Securities LLC and UBS Financial Services Inc. is an affiliate of UBS and, as such, has a “conflict of interest” in this offering within the meaning of FINRA Rule 5121. In addition, UBS will receive the net proceeds (excluding the underwriting discount) from the initial public offering of the Securities, thus creating an additional conflict of interest within the meaning of Rule 5121. Consequently, the offering is being conducted in compliance with the provisions of Rule 5121. Neither UBS Securities LLC nor UBS Financial Services Inc. is permitted to sell Securities in this offering to an account over which it exercises discretionary authority without the prior specific written approval of the account holder.

Structured Product Categorization

To help investors identify appropriate Structured Products (“Structured Products”), UBS organizes its Structured Products into four categories: Protection Strategies, Optimization Strategies, Performance Strategies and Leverage Strategies. The Securities are classified by UBS as a Performance Strategy for this purpose. The description below is intended to describe generally the four categories of Structured Products and the types of principal repayment features that may be offered on those products. This description should not be relied upon as a description of any particular Structured Product.

¨ Protection Strategies are structured to complement and provide the potential to outperform traditional fixed income instruments. These Structured Products are generally designed for investors with low to moderate risk tolerances.

¨ Optimization Strategies provide the opportunity to enhance market returns or yields and can be structured with full downside market exposure or with buffered or contingent downside market exposure. These structured products are generally designed for investors who can tolerate downside market risk.

¨ Performance Strategies provide efficient access to markets and can be structured with full downside market exposure or with buffered or contingent downside market exposure. These structured products are generally designed for investors who can tolerate downside market risk.

¨ Leverage Strategies provide leveraged exposure to the performance of an underlying asset. These Structured Products are generally designed for investors with high risk tolerances.

In order to benefit from any type of principal repayment feature, investors must hold the Securities to maturity.

Classification of Structured Products into categories is for informational purposes only and is not intended to guarantee particular results or performance.

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