The call price equals the principal amount per Security plus the applicable call return.

The table below reflects the call return rate of [•]% per annum. Amounts in the table below may have been rounded for ease of analysis.

*    Observation dates are subject to the market disruption event provisions discussed in the TAOS product supplement.

If the Securities have not been called and the final price of the underlying equity is equal to or greater than the trigger price, we will pay you an amount in cash at maturity equal to your principal amount.

If the Securities have not been called and the final price of the underlying equity is less than the trigger price, we will pay you an amount in cash that is significantly less than the principal amount, if anything, resulting in a loss of principal that is proportionate to the decline of the underlying equity, for an amount equal to $10 + ($10 × underlying return).

Final Price – Initial Price

         Initial Price

UBS Financial Services Inc.

Final Terms Supplement dated [•]

Prospectus supplement dated May 2, 2016:

TAOS Product Supplement dated May 2, 2016:

Prospectus dated April 29, 2016:

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

Higher call return rates are generally associated with a greater risk of loss — Greater expected volatility with respect to the underlying equity reflects a higher expectation as of the trade date that the price of the underlying equity could close below its trigger price on the final valuation date of the Securities. This greater expected risk will generally be reflected in a higher call return rate for the Securities. However, the underlying equity’s volatility can change significantly over the term of the Securities and the price of the underlying equity could fall sharply, which could result in a significant loss of principal.

The contingent repayment of your 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 underlying equity price is greater than the trigger price.

Your potential return on the Securities is limited to the call return — The return potential of the Securities is limited to the call return regardless of the appreciation of the underlying equity. In addition, because the call return increases the longer the Securities have been outstanding, the call price payable on earlier observation dates is less than the call price payable on later observation dates. The earlier the Securities are called, the lower your return will be. If the Securities are not called, you will not receive any call return. As an investor in the Securities, you will not participate in any appreciation in the price of the underlying equity even though you will be subject to the risk of a decline in the price of the underlying equity.

Credit risk of UBS — The Securities are unsubordinated, 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 investment.

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

Reinvestment risk — If your Securities are called early, the term of the Securities will be reduced and you will not receive any payment on the Securities after the applicable call settlement date. There is no guarantee that you would be able to reinvest the proceeds from an automatic call of the Securities at a comparable rate of return for a similar level of risk. To the extent you are able to reinvest such proceeds in an investment comparable to the Securities, you may incur transaction costs such as dealer discounts and hedging costs built into the price of the new securities. Because the Securities may be called as early as the first observation date after issuance, you should be prepared in the event the Securities are called early.

Market Risk — The price of the underlying equity can rise or fall sharply due to factors specific to that underlying equity and (i) in the case of common stock or American depositary shares, its issuer (the “underlying equity issuer”) or (ii) in the case of an exchange traded fund, the securities, futures contracts or physical commodities constituting the assets of that underlying equity. These factors 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. You, as an investor in the Securities, should make your own investigation into the underlying equity issuer and the underlying equity for your Securities. We urge you to review financial and other information filed periodically by the underlying equity issuer with the SEC.

Fair value considerations.

The issue price you pay for the Securities exceeds their estimated initial value — The issue price you pay for the Securities exceeds their estimated initial value as of the trade date due to the inclusion in the issue price of the underwriting discount, hedging costs, issuance costs and projected profits. As of the close of the relevant markets on the trade date, we determined the estimated initial value of the Securities by reference to our internal pricing models and it is set forth in this final terms supplement. The pricing models used to determine the estimated initial value of the Securities incorporate certain variables, including the price, volatility and expected dividends on the underlying equity, prevailing interest rates, the term of the Securities and our internal funding rate. Our internal funding rate is typically lower than the rate we would pay to issue conventional fixed or floating rate debt securities of a similar term. The underwriting discount, hedging costs, issuance costs, projected profits and the difference in rates will reduce the economic value of the Securities to you. Due to these factors, the estimated initial value of the Securities as of the trade date is less than the issue price you pay for the Securities.

The estimated initial value is a theoretical price; the actual price that you may be able to sell your Securities in any secondary market (if any) at any time after the trade date may differ from the estimated initial value — The value of your Securities at any time will vary based on many factors, including the factors described above and in “— Market risk” above and is impossible to predict. Furthermore, the pricing models that we use are proprietary and rely in part on certain assumptions about future events, which may prove to be incorrect. As a result, after the trade date, if you attempt to sell the Securities in the secondary market, the actual value you would receive may differ, perhaps materially, from the estimated initial value of the Securities determined by reference to our internal pricing models. The estimated initial value of the Securities does not represent a minimum or maximum price at which we or any of our affiliates would be willing to purchase your Securities in any secondary market at any time.

Our actual profits may be greater or less than the differential between the estimated initial value and the issue price of the Securities as of the trade date — We may determine the economic terms of the Securities, as well as hedge our obligations, at least in part, prior to pricing the Securities on the trade date. In addition, there may be ongoing costs to us to maintain and/or adjust any hedges and such hedges are often imperfect. Therefore, our actual profits (or potentially, losses) in issuing the Securities cannot be determined as of the trade date and any such differential between the estimated initial value and the issue price of the Securities as of the trade date does not reflect our actual profits. Ultimately, our actual profits will be known only at the maturity of the Securities.

Limited or no secondary market and secondary market price considerations.

There may be little or no secondary market for the Securities — The Securities will not be listed or displayed on any securities exchange or any electronic communications network. UBS Securities LLC and its affiliates intend, but are not required, to make a market for the Securities, 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. Furthermore, there can be no assurance that a secondary market for the Securities will develop. The estimated initial value of the Securities does not represent a minimum or maximum price at which we or any of our affiliates would be willing to purchase your Securities in any secondary market at any time.

The price at which UBS Securities LLC and its affiliates may offer to buy the Securities in the secondary market (if any) may be greater than UBS’ valuation of the Securities at that time, greater than any other secondary market prices provided by unaffiliated dealers (if any) and, depending on your broker, greater than the valuation provided on your customer account statements — For a limited period of time following the issuance of the Securities, UBS Securities LLC or its affiliates may offer to buy or sell such Securities at a price that exceeds (i) our valuation of the Securities at that time based on our internal pricing models, (ii) any secondary market prices provided by unaffiliated dealers (if any) and (iii) depending on your broker, the valuation provided on customer account statements. The price that UBS Securities LLC may initially offer to buy such Securities following issuance will exceed the valuations indicated by our internal pricing models due to the inclusion for a limited period of time of the aggregate value of the underwriting discount, hedging costs, issuance costs and theoretical projected trading profit. The portion of such amounts included in our price will decline to zero on a straight line basis over a period ending no later than the date specified under “Supplemental Plan of Distribution (Conflicts of Interest); Secondary Markets (if any).” Thereafter, if UBS Securities LLC or an affiliate makes secondary markets in the Securities, it will do so at prices that reflect our estimated value determined by reference to our internal pricing models at that time. The temporary positive differential relative to our internal pricing models arises from requests from and arrangements made by UBS Securities LLC with the selling agents of structured debt securities such as the Securities. As described above, UBS Securities LLC and its affiliates intend, but are not required, to make a market for the Securities and may stop making a market at any time. The price at which UBS Securities LLC or an affiliate may make secondary markets at any time (if at all) will also reflect its then current bid-ask spread for similar sized trades of structured debt securities. UBS Financial Services Inc. and UBS Securities LLC reflect this temporary positive differential on their customer statements. Investors should inquire as to the valuation provided on customer account statements provided by unaffiliated dealers.

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, force majeure and regulatory or judicial events; the creditworthiness of UBS and the then current bid-ask spread for the Securities.

Impact of fees and the use of internal funding rates rather than secondary market credit spreads on secondary market prices — All other things being equal, the use of the internal funding rates described above under “— Fair value considerations” as well as the inclusion in the issue price of the underwriting discount, hedging costs, issuance costs and any projected profits are, subject to the temporary mitigating effect of UBS Securities LLC’s and its affiliates’ market making premium, expected to reduce the price at which you may be able to sell the Securities in any secondary market.

Owning the Securities is not the same as owning the underlying equity — The return on your Securities may not reflect the return you would realize if you actually owned the underlying equity. For instance, you will not receive or be entitled to receive any dividend payments or other distributions on the underlying equity over the term of your Securities. Furthermore, the underlying equity may appreciate substantially during the term of your Securities and you will not participate in such appreciation.

No assurance that the investment view implicit in the Securities will be successful — It is impossible to predict whether and the extent to which the price of the underlying equity will rise or fall. The 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 risks of owning equities in general and the underlying equity in particular, and to assume the risk that, if the Securities are not automatically called, you will not receive any positive return on your Securities and you may lose some or all of your initial investment.

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, the trigger price and/or the final price of the underlying equity. 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 calculation agent may make any such adjustment, determination or calculation in a manner that differs from that discussed in the TAOS product supplement as necessary to achieve an equitable result. In the case of common stock or American depositary shares, following certain corporate events relating to the issuer of the underlying equity where such issuer is not the surviving entity, the amount of cash you receive at maturity (if any) may be based on the common stock or American depositary shares of a successor to the underlying equity issuer in combination with any cash or any other assets distributed to holders of the underlying equity in such corporate event. Additionally, if the issuer of the underlying equity becomes subject to (i) a reorganization event whereby the underlying equity is exchanged solely for cash, (ii) a merger or consolidation with UBS or any of its affiliates or (iii) an underlying equity is delisted or otherwise suspended from trading, the amount you receive at maturity may be based on the common stock or American depositary shares issued by another company. In the case of an exchange traded fund, following a delisting, suspension from trading or if an exchange traded fund is discontinued, the amount you receive at maturity may be based on a share of another exchange traded fund. The occurrence of these corporate 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” beginning on page PS-35 of the TAOS product supplement. Regardless of any of the events discussed above, any payment on the Securities is subject to the creditworthiness of UBS.

[ Exchange rate risk — The Securities are linked to the American depositary shares of a non-U.S. company. Because American depositary shares are denominated in U.S. dollars but represent non-U.S. equity securities that are denominated in a non-U.S. currency, changes in currency exchange rates may negatively impact the value of the American depositary shares. The value of the non-U.S. currency 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, non-U.S. governments, central banks or supranational entities, the imposition of currency controls or other national or global political or economic developments. Therefore, adverse changes in exchange rates may result in reduced returns for Securities linked to American depositary shares.]

[ Risks associated with non-U.S. securities markets — The Securities are linked to the American depositary shares of a non-U.S. company. Because non-U.S. equity securities underlying the American depositary shares may be publicly traded in the applicable non-U.S. countries and are denominated in currencies other than U.S. dollars, investments in Securities linked to American depositary shares involve particular risks. For example, the non-U.S. securities markets may be more volatile than the U.S. securities markets, and market developments may affect these markets differently from the United States or other securities markets. Direct or indirect government intervention to stabilize the securities markets outside the United States, as well as cross-shareholdings in certain companies, may affect trading prices and trading volumes in those markets. Also, the public availability of information concerning the non-U.S. issuers may vary depending on their home jurisdiction and the reporting requirements imposed by their respective regulators. In addition, the non-U.S. issuers may be subject to accounting, auditing and financial reporting standards and requirements that differ from those applicable to United States reporting companies. Securities prices generally are subject to political, economic, financial and social factors that apply to the markets in which they trade and, to a lesser extent, international markets. Securities prices outside the United States are subject to political, economic, financial and social factors that apply in non-U.S. countries. These factors, which could negatively affect non-U.S. securities markets, include the possibility of changes in a non-U.S. government’s economic and fiscal policies, the possible imposition of, or changes in, currency exchange laws or other 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, non-U.S. economies may differ favorably or unfavorably from the United States economy in important respects such as growth of gross national product, rate of inflation, capital reinvestment, resources and self-sufficiency.]

[ There are important differences between the American depositary shares and the ordinary shares of a non-U.S. company — The Securities are linked to the American depositary shares of a non-U.S. company. There are important differences between the rights of holders of American depositary shares and the rights of holders of the ordinary shares. The American depositary shares are issued pursuant to a deposit agreement, which sets forth the rights and responsibilities of the depositary, the non-U.S. company, and holders of the American depositary shares, which may be different from the rights of holders of the ordinary shares. For example, a company may make distributions in respect of ordinary shares that are not passed on to the holders of its American depositary shares. Any such differences between the rights of holders of the American depositary shares and the rights of holders of the ordinary shares of the non-U.S. company may be significant and may materially and adversely affect the value of the American depositary shares and, as a result, the value of your Securities.]

[ Risks associated with non-U.S. companies — The Securities are linked to the common stock of a non-U.S. company that is listed on a U.S. exchange. An investment in the Securities linked to the value of non-U.S. companies involves risks associated with the home country of such non-U.S. company. The prices of such non-U.S. company’s common stock may be affected by political, economic, financial and social factors in the home country of such non-U.S. company, including changes in such country’s government, economic and fiscal policies, currency exchange laws or other laws or restrictions, which could affect the value of the Securities.]

[ Risks associated with emerging market companies — The underlying equity issuer is a company organized in an emerging market country. 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.]

[[ The value of the underlying equity may not completely track the value of the securities, futures contracts or physical commodities in which such exchange traded fund invests — Although the trading characteristics and valuations of the underlying equity will usually mirror the characteristics and valuations of the securities, futures contracts or physical commodities in which such exchange traded fund invests, its value may not completely track the value of such securities, futures contracts or physical commodities. The value of the underlying equity will reflect transaction costs and fees that the securities, futures contracts or physical commodities in which that exchange traded fund 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 such 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, futures contracts or physical commodities 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 its 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.]]

There is no affiliation between the underlying equity issuer, or for Securities linked to exchange traded funds, the issuers of the constituent stocks comprising the underlying equity (the “underlying equity constituent stock issuers”), and UBS, and UBS is not responsible for any disclosure by such issuer(s) — We and our affiliates may currently, or from time to time in the future engage in business with the underlying equity issuer or, if applicable, any underlying equity constituent stock issuers. However, we are not affiliated with the underlying equity issuer or any underlying equity constituent stock issuers and are not responsible for such issuer’s public disclosure of information, whether contained in SEC filings or otherwise. You, as an investor in the Securities, should make your own investigation into the underlying equity issuer or, if applicable, each underlying equity constituent stock issuer. Neither the underlying equity issuer nor any underlying equity constituent stock issuer is involved in the Securities offered hereby in any way and has no obligation of any sort with respect to your Securities. Such issuer(s) 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.

Potential UBS impact on the market price of the underlying equity — Trading or transactions by UBS or its affiliates in the underlying equity and/or over-the-counter options, futures or other instruments with returns linked to the performance of the underlying equity may adversely affect the market price of the underlying equity and, therefore, the market value of your 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. The calculation agent, an affiliate of UBS, will determine whether the final price is less than the trigger price and accordingly the payment at maturity on your Securities. The calculation agent may also postpone the determination of the closing price of the underlying equity if a market disruption event occurs and is continuing on any observation date (including the final valuation date) and may make adjustments to the initial price, trigger price, final price and/or the underlying equity itself for certain corporate events affecting the underlying equity. For more information, see the section “General Terms of the Securities — Antidilution Adjustments” beginning on page PS-35 of the TAOS product supplement. As UBS determines the economic terms of the Securities, including the call return rate and trigger price, and such terms include hedging costs, issuance costs and projected profits, the Securities represent a package of economic terms. There are other potential conflicts of interest insofar as an investor could potentially get better economic terms if that investor entered into exchange-traded and/or OTC derivatives or other instruments with third parties, assuming that such instruments were available and the investor had the ability to assemble and enter into such instruments.

Potentially inconsistent research, opinions or recommendations by UBS — UBS and its affiliates may publish research or express opinions or provide recommendations that are inconsistent with purchasing or holding the Securities, and which may be revised without notice. Any research, opinions or recommendations expressed by UBS or its affiliates may not be consistent with each other and may influence the value of the Securities. 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.

Under certain circumstances, the Swiss Financial Market Supervisory Authority (“FINMA”) has the power to take actions that may adversely affect the Securities — Pursuant to article 25 et seq. of the Swiss Banking Act, FINMA has broad statutory powers to take measures and actions in relation to UBS if it (i) is overindebted, (ii) has serious liquidity problems or (iii) fails to fulfill the applicable capital adequacy provisions after expiration of a deadline set by FINMA. If one of these prerequisites is met, the Swiss Banking Act grants significant discretion to FINMA to open restructuring proceedings or liquidation (bankruptcy) proceedings in respect of, and/or impose protective measures in relation to, UBS. In particular, a broad variety of protective measures may be imposed by FINMA, including a bank moratorium or a maturity postponement, which measures may be ordered by FINMA either on a stand-alone basis or in connection with restructuring or liquidation proceedings. In a restructuring proceeding, the resolution plan may, among other things, (a) provide for the transfer of UBS’s assets or a portion thereof, together with debts and other liabilities, and contracts of UBS, to another entity, (b) provide for the conversion of UBS’s debt and/or other obligations, including its obligations under the Securities, into equity, and/or (c) potentially provide for haircuts on obligations of UBS, including its obligations under the Securities. Although no precedent exists, if one or more

measures under the revised regime were imposed, such measures may have a material adverse effect on the terms and market value of the Securities and/or the ability of UBS to make payments thereunder.

Dealer incentives — UBS and its 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 which may serve as an incentive to sell these Securities instead of other investments. We will pay total underwriting compensation of [•]% per Security to any of our affiliates acting as agents or dealers in connection with the distribution of the Securities. Given that UBS Securities LLC and its affiliates temporarily maintain a market making premium, it may have the effect of discouraging UBS Securities LLC and its affiliates from recommending sale of your Securities in the secondary market.

Uncertain tax treatment — Significant aspects of the tax treatment of the Securities are uncertain. You should read carefully the sections entitled “What are the Tax Consequences of the Securities” in the prospectus supplement and “Supplemental U.S. Tax Considerations” beginning on page PS-48 of the TAOS product supplement and consult your tax advisor about your tax situation.