Subject to Completion

Dated April 23, 2019

PRELIMINARY TERMS SUPPLEMENT

Filed Pursuant to Rule 424(b)(2)

Registration Statement No. 333-225551

Preliminary Terms Supplement

UBS AG Buffered Return Optimization Securities

UBS AG $ Securities linked to the common stock of Nabors Industries Ltd. due on or about April 28, 2020

Indicative Terms

Issuer

UBS AG, London Branch

Term

Approximately 12 months.

Underlying Asset

The common stock of Nabors Industries Ltd.

Trade Date

April 23, 2019 (subject to postponement in the event of a market disruption event, as described in the accompanying product supplement).

Settlement Date

April 25, 2019 (subject to postponement in the event of a market disruption event, as described in the accompanying product supplement).

Final Valuation Date

April 23, 2020 (subject to postponement in the event of a market disruption event, as described in the accompanying product supplement).

Maturity Date

April 28, 2020 (subject to postponement in the event of a market disruption event, as described in the accompanying product supplement).

Principal Amount

$10 per Security. The Securities are offered at a minimum investment of 100 Securities at $10 per Security (representing a $1,000 investment) and integral multiples of $10 in excess thereof.

Payment at Maturity (per Security)

On the maturity date,

if the underlying return is positive, UBS will pay you a cash payment for each Security you hold equal to $10 + ($10 x the lesser of (a) Underlying Return x Multiplier and (b) Maximum Gain);

if the underlying return is zero or negative and the percentage decline from the initial level to the final level is equal to or less than the buffer percentage, UBS will pay you a cash payment for each Security you hold equal to your principal amount; or

if the underlying return is negative and the percentage decline from the initial level to the final level is greater than the buffer percentage, UBS will pay you a cash payment for each Security you hold equal to $10 + [$10 x (Underlying Return + Buffer Percentage)].

Investors will be exposed to any percentage decline in the level of the underlying asset in excess of the buffer percentage from the trade date to the final valuation date. Specifically, if the percentage decline of the underlying asset from the initial level to the final level is greater than the buffer percentage, you will lose a percentage of your principal amount equal to the percentage decline in excess of the buffer percentage, and in extreme situations, you could lose almost all of your initial investment.

Underlying Return

The quotient, expressed as a percentage, of the following formula:

( Final Level - Initial Level ) / Initial Level

Initial Level

The closing level of the underlying asset on the trade date, as determined by the calculation agent and as may be adjusted in the case of certain corporate events, as described in the accompanying product supplement.

Final Level

The closing level of the underlying asset on the final valuation date, as determined by the calculation agent and subject to adjustments in the case of certain corporate events, as described in the accompanying product supplement.

Closing Level

On any trading day, generally the last reported sale price (or, in the case of NASDAQ, the official closing price) of the underlying asset during the principal trading session on the principal national securities exchange on which it is listed for trading, as determined by the calculation agent.

Multiplier

5.00

Maximum Gain

22.11% to 24.27%. The actual maximum gain will be set on the trade date.

Buffer Percentage

30.00%

CUSIP

[]

ISIN

[]

Valoren

[]

Offering of Securities

Issue Price to Public

Underwriting Discount

Proceeds to UBS AG

Total

Per Security

Total

Per Security

Total

Per Security

Securities linked to the common stock of Nabors Industries Ltd.

$

100%

$

2.00%

$

98.00%

UBS Financial Services Inc.

UBS Investment Bank

Additional Information About UBS and the Securities

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BROS Prospectus Supplement dated November 1, 2018:

http://www.sec.gov/Archives/edgar/data/1114446/000091412118002107/ub46175266-424b2.htm

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Market-Linked Securities product supplement dated October 31, 2018:

http://www.sec.gov/Archives/edgar/data/1114446/000091412118002085/ub47016353-424b2.htm

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Prospectus dated October 31, 2018:

http://www.sec.gov/Archives/edgar/data/1114446/000119312518314003/d612032d424b3.htm

Key Risks

An investment in the Securities involves significant risks. Some of the risks that apply to the Securities are summarized here and are comparable to the corresponding risks discussed in the “Key Risks” section of the BROS prospectus supplement, but we urge you to read the more detailed explanation of risks relating to the Securities generally in the “Risk Factors” section of the accompanying product supplement. We also urge you to consult your investment, legal, tax, accounting and other advisors before you invest in the Securities.

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Risk of loss at maturity - The Securities differ from ordinary debt securities in that UBS will not necessarily pay the principal amount of the Securities. UBS will only pay you the principal amount of your Securities at maturity if the percentage decline of the underlying asset from the initial level to the final level is equal to or less than the buffer percentage. If the percentage decline of the underlying asset from the initial level to the final level is greater than the buffer percentage, you will lose a percentage of your principal amount equal to the percentage decline in excess of the buffer percentage, and in extreme situations, you could lose almost all of your initial investment.

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The stated payout from the issuer applies only if you hold your Securities to 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 then-current percentage decline of the underlying asset from the initial level is equal to or less than the buffer percentage at that time.

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The multiplier applies only if you hold your Securities to 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 multiplier, and the return you realize may be less than the return of the underlying asset times the multiplier even if the then-current underlying return is positive and does not exceed the maximum gain at that time. You can receive the full benefit of the multiplier, subject to the maximum gain, from UBS only if you hold your Securities to maturity.

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Your potential return on the Securities is limited to the maximum gain - The return potential of the Securities is limited to the maximum gain. Therefore, you will not benefit from any positive underlying return in excess of an amount that, when multiplied by the multiplier, exceeds the maximum gain and your return on the Securities may be less than a direct investment in the underlying asset.

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

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Greater expected volatility generally indicates an increased risk of loss at maturity - "Volatility” refers to the frequency and magnitude of changes in the level of the underlying asset. The greater the expected volatility of the underlying asset as of the trade date, the greater the expectation is as of the trade date that the percentage decline from the initial level to the final level could be greater than the buffer percentage and, as a consequence, indicates an increased risk of loss. However, the underlying asset’s volatility can change significantly over the term of the Securities, and a relatively higher buffer percentage may not necessarily indicate that the Securities have a greater likelihood of a return of principal at maturity. You should be willing to accept the downside market risk of the underlying asset and the potential to lose some or all of your initial investment.

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Credit risk of UBS - The Securities are unsubordinated, unsecured debt obligations of 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 at maturity, depends on the ability of UBS to satisfy its obligations as they come due. As a result, UBS’s actual and perceived creditworthiness may affect the market value of the Securities. If 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 all of your initial investment.

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Single equity risk - The return on the Securities, which may be positive or negative, is directly linked to the performance of the underlying asset. The level of the underlying asset can rise or fall sharply due to factors specific to that underlying asset and the issuer of the underlying asset (the "underlying asset issuer"), such as equity 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 conduct your own investigation into the respective underlying asset issuer and the underlying asset for your Securities. For additional information regarding the underlying asset issuer, please see "Information about the Underlying Asset" and "Nabors Industries Ltd." in this preliminary terms supplement and the respective underlying asset issuer's SEC filings referred to in these sections. We urge you to review financial and other information filed periodically by the underlying asset issuer with the SEC.

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Fair value considerations.

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The issue price you pay for the Securities will exceed their estimated initial value - The issue price you pay for the Securities will exceed 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 will determine the estimated initial value of the Securities by reference to our internal pricing models and it will be set forth in the final terms supplement. The pricing models used to determine the estimated initial value of the Securities incorporate certain variables, including the level and volatility of the underlying asset, the expected dividends of the underlying asset, 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 will be less than the issue price you pay for the Securities.

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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 “Single equity 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.

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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.

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Limited or no secondary market and secondary market price considerations.

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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. There can be no assurance that a secondary market for the Securities will develop. UBS Securities LLC and its affiliates may make a market in each 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 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.

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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 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.

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Price of Securities prior to maturity - The market price of the Securities will be influenced by many unpredictable and interrelated factors, including the level of the underlying asset; the volatility of the underlying asset; the dividend rate paid on the underlying asset; 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.

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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.

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Owning the Securities is not the same as owning the underlying asset - The return on your Securities may not reflect the return you would realize if you actually owned the underlying asset. For instance, you will not benefit from any positive underlying return in excess of an amount that, when multiplied by the multiplier, exceeds the maximum gain. Furthermore, you will not receive or be entitled to receive any dividend payments or other distributions during the term of the Securities, and any such dividends or distributions will not be factored into the calculation of the payment at maturity on your Securities. In addition, as an owner of the Securities, you will not have voting rights or any other rights that a holder of the underlying asset may have.

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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 level of the underlying asset will rise or fall and there can be no assurance that any percentage decline of the underlying asset from the initial level to the final level will be equal to or less than the buffer percentage. The level of the underlying asset will be influenced by complex and interrelated political, economic, financial and other factors that affect the underlying asset issuer. You should be willing to accept the risks of owning equities in general and the underlying asset in particular, and to assume the risk of losing some or almost all of your initial investment.

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The calculation agent can make antidilution and reorganization adjustments that affect the payment to you at maturity - For antidilution and reorganization events affecting the underlying asset, the calculation agent may make adjustments to the initial level and/or the final level, as applicable and any other term of the Securities. However, the calculation agent will not make an adjustment in response to every corporate event that could affect the underlying asset. If an event occurs that does not require the calculation agent to make an adjustment, the value of the Securities and your payment at maturity 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 accompanying product supplement, the BROS prospectus supplement or this preliminary terms supplement as necessary to achieve an equitable result. Following certain reorganization events relating to the underlying asset issuer where such issuer is not the surviving entity, the amount of cash you receive at maturity may be based on the equity security of a successor to the respective underlying asset issuer in combination with any cash or any other assets distributed to holders of the underlying asset in such reorganization event. If the underlying asset issuer becomes subject to (i) a reorganization event whereby the underlying asset is exchanged solely for cash, (ii) a merger or consolidation with UBS or any of its affiliates, or (iii) the underlying asset is delisted or otherwise suspended from trading, the amount you receive at maturity may be based on a substitute security. The occurrence of any antidilution or reorganization event and the consequent adjustments may materially and adversely affect the value of the Securities and your payment at maturity, if any. For more information, see the sections “General Terms of the Securities - Antidilution Adjustments for Securities Linked to an Underlying Asset or Equity Basket Asset” and “- Reorganization Events for Securities Linked to an Underlying Asset or Equity Basket Asset” in the accompanying product supplement.

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Risks associated with non-U.S. securities markets - The Securities are linked to the ADRs of a non-U.S. company or to the common stock of a non-U.S. company traded on a U.S. exchange. An investment in securities linked directly or indirectly to the value of non-U.S. equity securities involves 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 U.S. or other securities markets. Direct or indirect government intervention to stabilize the securities markets outside the U.S., 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. 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, non-U.S. markets. Securities prices outside the U.S. 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 U.S. economy in important respects such as growth of gross national product, rate of inflation, capital reinvestment, resources and self-sufficiency.

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There is no affiliation between the underlying asset issuer and UBS, and UBS is not responsible for any disclosure by such issuer - We and our affiliates may currently, or from time to time in the future engage in business with the underlying asset issuer. However, we are not affiliated with the underlying asset issuer 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 conduct your own investigation into the underlying asset and the underlying asset issuer. The underlying asset issuer is not involved in the Securities offered hereby in any way and has no obligation of any sort with respect to your Securities. The underlying asset issuer has no obligation to take your interests into consideration for any reason, including when taking any corporate actions that might affect the value of, and any amounts payable on, your Securities.

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Potential UBS impact on the market price of the underlying asset - Trading or transactions by UBS or its affiliates in the underlying asset, listed and/or over-the-counter options, futures or other instruments with returns linked to the performance of the underlying asset may adversely affect the market price of the underlying asset and, therefore, the market value of, and any amounts payable on, your Securities.

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Potential conflict of interest - UBS and its affiliates may engage in business with the issuer of the underlying asset, 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. The calculation agent will determine the underlying return and the payment at maturity based on the closing level of the underlying asset on the final valuation date. The calculation agent can postpone the determination of the initial level, buffer percentage and/or maximum gain on the trade date and the final level on the final valuation date, if a market disruption event occurs and is continuing on that day and may make adjustments to the initial level, final level and the underlying asset itself for antidilution and reorganization events affecting the underlying asset. For more information, see the "General Terms of the Securities - Antidilution Adjustments for Securities Linked to an Underlying Equity or Equity Basket Asset" and " - Reorganization Events for Securities Linked to an Underlying Equity or Equity Basket Asset" in the accompanying product supplement. As UBS determines the economic terms of the Securities, including the maximum gain, buffer percentage and multiplier, and such terms include the underwriting discount, 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.

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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 asset to which the Securities are linked.

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The Securities are not bank deposits - An investment in the Securities carries risks which are very different from the risk profile of a bank deposit placed with UBS or its affiliates. The Securities have different yield and/or return, liquidity and risk profiles and would not benefit from any protection provided to deposits.

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If UBS experiences financial difficulties, FINMA has the power to open restructuring or liquidation proceedings in respect of, and/or impose protective measures in relation to, UBS, which proceedings or 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 - The Swiss Financial Market Supervisory Authority (“FINMA”) has broad statutory powers to take measures and actions in relation to UBS if (i) it concludes that there is justified concern that UBS is over-indebted or has serious liquidity problems or (ii) UBS fails to fulfil the applicable capital adequacy requirements (whether on a standalone or consolidated basis) after expiry of a deadline set by FINMA. If one of these pre-requisites is met, FINMA is authorized to open restructuring proceedings or liquidation (bankruptcy) proceedings in respect of, and/or impose protective measures in relation to, UBS. The Swiss Banking Act grants significant discretion to FINMA in connection with the aforementioned proceedings and measures. 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. The resolution regime of the Swiss Banking Act is further detailed in the FINMA Banking Insolvency Ordinance (“BIO-FINMA”). In a restructuring proceeding, FINMA, as resolution authority, is competent to approve the resolution plan. The resolution plan may, among other things, provide for (a) the transfer of all or a portion of UBS’s assets, debts, other liabilities and contracts (which may or may not include the contractual relationship between UBS and the holders of Securities) to another entity, (b) a stay (for a maximum of two business days) on the termination of contracts to which UBS is a party, and/or the exercise of (w) rights to terminate, (x) netting rights, (y) rights to enforce or dispose of collateral or (z) rights to transfer claims, liabilities or collateral under contracts to which UBS is a party, (c) the conversion of UBS’s debt and/or other obligations, including its obligations under the Securities, into equity (a “debt-to-equity” swap), and/or (d) the partial or full write-off of obligations owed by UBS (a “write-off”), including its obligations under the Securities. The BIO-FINMA provides that a debt-to-equity swap and/or a write-off of debt and other obligations (including the Securities) may only take place after (i) all debt instruments issued by UBS qualifying as additional tier 1 capital or tier 2 capital have been converted into equity or written-off, as applicable, and (ii) the existing equity of UBS has been fully cancelled. While the BIO-FINMA does not expressly address the order in which a write-off of debt instruments other than debt instruments qualifying as additional tier 1 capital or tier 2 capital should occur, it states that debt-to-equity swaps should occur in the following order: first, all subordinated claims not qualifying as regulatory capital; second, all other claims not excluded by law from a debt-to-equity swap (other than deposits); and third, deposits (in excess of the amount privileged by law). However, given the broad discretion granted to FINMA as the resolution authority, any restructuring plan in respect of UBS could provide that the claims under or in connection with the Securities will be partially or fully converted into equity or written-off, while preserving other obligations of UBS that rank pari passu with, or even junior to, UBS’s obligations under the Securities. Consequently, holders of Securities may lose all of some of their investment in the Securities. In the case of restructuring proceedings with respect to a systemically important Swiss bank (such as UBS), the creditors whose claims are affected by the restructuring plan will not have a right to vote on, reject, or seek the suspension of the restructuring plan. In addition, if a restructuring plan has been approved by FINMA, the rights of a creditor to seek judicial review of the restructuring plan (e.g., on the grounds that the plan would unduly prejudice the rights of holders of Securities or otherwise be in violation of the Swiss Banking Act) are very limited. In particular, a court may not suspend the implementation of the restructuring plan. Furthermore, even if a creditor successfully challenges the restructuring plan, the court can only require the relevant creditor to be compensated ex post and there is currently no guidance as to on what basis such compensation would be calculated or how it would be funded.

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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 in an amount equal to the underwriting discount indicated on the cover hereof 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.

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Uncertain tax treatment - Significant aspects of the tax treatment of the Securities are uncertain. You should consult your tax advisor about your own tax situation. See the sections entitled ‘‘What are the Tax Consequences of the Securities?” herein and in the prospectus supllement and ‘‘Material U.S. Federal Income Tax Consequences” in the accompanying product supplement.

Information about the Underlying Asset

All disclosures regarding the underlying asset are derived from publicly available information. UBS has not conducted any independent review or due diligence of any publicly available information with respect to the underlying asset. You should make your own investigation into the underlying asset.

The underlying asset is registered under the Securities Act of 1933, the Securities Exchange Act of 1934, and/or the Investment Company Act of 1940, each as amended. Companies with securities registered with the SEC are required to file financial and other information specified by the SEC periodically. Information filed by the underlying asset issuer with the SEC can be reviewed electronically through a website maintained by the SEC. The address of the SEC’s website is http://www.sec.gov. Information filed with the SEC by the underlying asset issuer can be located by reference to its SEC file number provided below. In addition, information filed with the SEC can be inspected and copied at the Public Reference Section of the SEC, 100 F Street, N.E., Room 1580, Washington, D.C. 20549. Copies of this material can also be obtained from the Public Reference Section, at prescribed rates.

Information from outside sources is not incorporated by reference in, and should not be considered part of, this preliminary terms supplement or any accompanying prospectus, product supplement or prospectus supplement. UBS has not conducted any independent review or due diligence of any publicly available information with respect to the underlying asset.

Nabors Industries Ltd.

Quarter Begin

Quarter End

Quarterly High

Quarterly Low

Quarterly Close

07/01/2014

09/30/2014

$30.04

$22.76

$22.76

10/01/2014

12/31/2014

$22.17

$10.00

$12.98

01/02/2015

03/31/2015

$13.90

$10.00

$13.65

04/01/2015

06/30/2015

$16.70

$14.03

$14.43

07/01/2015

09/30/2015

$13.81

$9.16

$9.45

10/01/2015

12/31/2015

$12.08

$7.73

$8.51

01/04/2016

03/31/2016

$9.49

$5.53

$9.20

04/01/2016

06/30/2016

$10.85

$7.93

$10.05

07/01/2016

09/30/2016

$12.16

$8.61

$12.16

10/03/2016

12/30/2016

$17.49

$11.33

$16.40

01/03/2017

03/31/2017

$18.19

$12.03

$13.07

04/03/2017

06/30/2017

$14.18

$7.42

$8.14

07/03/2017

09/29/2017

$8.62

$6.27

$8.07

10/02/2017

12/29/2017

$7.99

$5.48

$6.83

01/02/2018

03/29/2018

$8.45

$6.44

$6.99

04/02/2018

06/29/2018

$8.61

$6.20

$6.41

07/02/2018

09/28/2018

$6.72

$5.70

$6.16

10/01/2018

12/31/2018

$6.54

$1.89

$2.00

01/02/2019

03/29/2019

$3.70

$2.19

$3.44

04/01/2019*

04/22/2019*

$3.98

$3.68

$3.98

What are the Tax Consequences of the Securities?

Supplemental Plan of Distribution (Conflicts of Interest); Secondary Markets (if any)

We will agree to sell to UBS Securities LLC and UBS Securities LLC will agree to purchase, all of the Securities at the issue price to the public less the underwriting discount indicated on the cover of the final terms supplement, the document that will be filed pursuant to Rule 424(b) containing the final pricing terms of the Securities. UBS Securities LLC will agree to resell all of the Securities to UBS Financial Services Inc. at a discount from the issue price to the public equal to the underwriting discount indicated on the cover of the final terms supplement.

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 and, thus creates an additional conflict of interest within the meaning of FINRA 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 the offering to an account over which it exercises discretionary authority without the prior specific written approval of the account holder.

UBS Securities LLC and its affiliates may offer to buy or sell the Securities in the secondary market (if any) at prices greater than UBS’ internal valuation - The value of the Securities at any time will vary based on many factors that cannot be predicted. However, the price (not including UBS Securities LLC’s or any affiliate’s customary bid-ask spreads) at which UBS Securities LLC or any affiliate would offer to buy or sell the Securities immediately after the trade date in the secondary market is expected to exceed the estimated initial value of the Securities as determined by reference to our internal pricing models. The amount of the excess will decline to zero on a straight line basis over a period ending no later than 3 months after the trade date, provided that UBS Securities LLC may shorten the period based on various factors, including the magnitude of purchases and other negotiated provisions with selling agents. Notwithstanding the foregoing, UBS Securities LLC and its affiliates are not required to make a market for the Securities and may stop making a market at any time. For more information about secondary market offers and the estimated initial value of the Securities, see “Key Risks - Fair value considerations” and “Key Risks - Limited or no secondary market and secondary market price considerations” on pages 4 and 5 of this preliminary terms supplement.

Prohibition of Sales to EEA Retail Investors — The Securities are not intended to be offered, sold or otherwise made available to and should not be offered, sold or otherwise made available to any retail investor in the European Economic Area (“EEA”). For these purposes, a retail investor means a person who is one (or more) of: (i) a retail client as defined in point (11) of Article 4(1) of Directive 2014/65/EU, as amended (“MiFID II”); (ii) a customer within the meaning of Directive 2002/92/EC, as amended, where that customer would not qualify as a professional client as defined in point (10) of Article 4(1) of MiFID II; or (iii) not a qualified investor as defined in Directive 2003/71/EC, as amended. Consequently no key information document required by Regulation (EU) No 1286/2014 (as amended, the “PRIIPs Regulation”) for offering or selling the Securities or otherwise making them available to retail investors in the EEA has been prepared and therefore offering or selling the Securities or otherwise making them available to any retail investor in the EEA may be unlawful under the PRIIPs Regulation.

Indicative Terms

1

Additional Information About UBS and the Securities

3

Key Risks

4

Information About the Underlying Asset

7

Nabors Industries Ltd.

7

Supplemental Plan of Distribution (Conflicts of Interest); Secondary Markets (if any)

9

Prospectus Supplement

Investment Description

i

Features

i

Security Offerings

i

Additional Information About UBS and the Securities

ii

Investor Suitability

1

Common Terms for Each Offering of the Securities

2

Investment Timeline

3

Key Risks

4

Hypothetical Performance Scenarios

9

What are the Tax Consequences of the Securities ?

11

Information About the Underlying Asset

14

Supplemental Plan of Distribution (Conflicts of Interest); Secondary Markets (if any)

15

Annex A – Form of Final Terms Supplement

A-2

Annex B – UBS Equity Investor - Investment Guide

B-2

Product Supplement

Product Supplement Summary

PS-1

Specific Terms of Each Security Will Be Described in the Applicable Supplements

PS-1

The Securities are Part of a Series

PS-1

Denomination

PS-2

Coupons

PS-2

Early Redemption

PS-3

Payment at Maturity for the Securities

PS-3

Defined Terms Relating to Payment on the Securities

PS-3

Valuation Dates

PS-5

Valuation Periods

PS-6

Payment Dates

PS-6

Closing Level

PS-7

Intraday Level

PS-7

The Tax Consequences of an Investment in the Securities is Uncertain

PS-8

Risk Factors

PS-9

General Terms of the Securities

PS-9

Specific Terms of Each Security Will Be Described in the Applicable Supplements

PS-28

The Securities are Part of a Series

PS-28

Denomination

PS-28

Coupons

PS-29

Early Redemption

PS-29

Payment at Maturity for Securities

PS-30

Defined Terms Relating to Payment on the Securities

PS-30

Valuation Dates

PS-32

Valuation Periods

PS-33

Payment Dates

PS-33

Closing Level

PS-33

Intraday Level

PS-34

Market Disruption Events

PS-35

Discontinuance of or Adjustments to an Underlying Index; Alteration of Method of Calculation

PS-39

Antidilution Adjustments for Securities Linked to an Underlying Equity or Equity Basket Asset

PS-39

Reorganization Events for Securities Linked to an Underlying Equity or Equity Basket Asset

PS-43

Delisting or Suspension of Trading in an Underlying Equity

PS-46

Delisting of ADRs or Termination of ADR Facility

PS-46

Delisting, Discontinuance or Modification of an ETF

PS-47

Redemption Price Upon Optional Tax Redemption

PS-48

Default Amount on Acceleration

PS-48

Default Amount

PS-48

Default Quotation Period

PS-49

Qualified Financial Institutions

PS-49

Manner of Payment and Delivery

PS-49

Regular Record Dates for Coupons

PS-49

Trading Day

PS-49

Business Day

PS-49

Role of Calculation Agent

PS-50

Booking Branch

PS-50

Use of Proceeds and Hedging

PS-51

Material U.S. Federal Income Tax Consequences

PS-52

Certain ERISA Considerations

PS-74

Supplemental Plan of Distribution (Conflict of Interest)

PS-75

Prospectus

Introduction

1

Cautionary Note Regarding Forward-Looking Statements

3

Incorporation of Information About UBS AG

4

Where You Can Find More Information

5

Presentation of Financial Information

6

Limitations on Enforcement of U.S. Laws Against UBS AG, Its Management and Others

6

UBS

7

Swiss Regulatory Powers

10

Use of Proceeds

11

Description of Debt Securities We May Offer

12

Description of Warrants We May Offer

32

Legal Ownership and Book-Entry Issuance

49

Considerations Relating to Indexed Securities

52

Considerations Relating to Securities Denominated or Payable in or Linked to a Non-U.S. Dollar Currency

55

U.S. Tax Considerations

58

Tax Considerations Under the Laws of Switzerland

69

Benefit Plan Investor Considerations

71

Plan of Distribution

73

Conflicts of Interest

75

Validity of the Securities

76

Experts

76