485BPOS

As filed with the Securities and Exchange Commission on January 15, 2013

1933 Act Registration No. 33-39659

1940 Act Registration No. 811-6292

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM N-lA

REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933     x

Pre-Effective Amendment No.       o

Post-Effective Amendment No. 50  x

REGISTRATION STATEMENT UNDER THE INVESTMENT COMPANY ACT OF 1940 x

Amendment No. 50

UBS INVESTMENT TRUST

(Exact Name of Registrant as Specified in Charter)

1285 Avenue of the Americas

New York, New York 10019-6028

(Address of Principal Executive Offices)

Registrant’s telephone number, including area code: (212) 882-3000

MARK F. KEMPER, ESQ.

UBS Global Asset Management (Americas) Inc.

1285 Avenue of the Americas

New York, New York 10019-6028

(Name and Address of Agent for Service)

Copies to:

JACK W. MURPHY, ESQ.

Dechert LLP

1900 K Street, N.W.

Washington, D.C. 20006

Approximate Date of Proposed Public Offering: Effective Date of this Post-Effective Amendment.

It is proposed that this filing will become effective:

x Immediately upon filing pursuant to Rule 485(b)

o On                    pursuant to Rule 485(b)

o 60 days after filing pursuant to Rule 485(a)(1)

o On                    pursuant to Rule 485(a)(1)

o 75 days after filing pursuant to Rule 485(a)(2)

o On                      pursuant to Rule 485(a)(2)

If appropriate, check the following box:

o this post-effective amendment designates a new effective date for a previously filed post-effective amendment.

Title of Securities Being Registered: Class A, C and Y Shares of Beneficial Interest of UBS U.S. Allocation Fund.

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933 and the Investment Company Act of 1940, the Registrant certifies that it meets all of the requirements for effectiveness of this Post-Effective Amendment to its Registration Statement under Rule 485(b) under the Securities Act of 1933 and has duly caused this Post-Effective Amendment No. 50 to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of New York and State of New York, on the 15th day of January, 2013.

UBS INVESTMENT TRUST
By:	/s/ Eric Sanders
	Eric Sanders
	Vice President and Assistant Secretary

Pursuant to the requirements of the Securities Act of 1933, this Post-Effective Amendment has been signed below by the following persons in the capacities and on the dates indicated:

SIGNATURE	TITLE	DATE
/s/ Richard Q. Armstrong	Trustee and Chairman of the Board of Trustees	January 15, 2013
Richard Q. Armstrong*
/s/ Alan S. Bernikow	Trustee	January 15, 2013
Alan S. Bernikow*
/s/ Richard R. Burt	Trustee	January 15, 2013
Richard R. Burt*
/s/ Mark E. Carver	President	January 15, 2013
Mark E. Carver*
/s/ Thomas Disbrow	Vice President and Treasurer	January 15, 2013
Thomas Disbrow
/s/ Meyer Feldberg	Trustee	January 15, 2013
Meyer Feldberg*
/s/ Bernard H. Garil	Trustee	January 15, 2013
Bernard H. Garil*
/s/ Heather R. Higgins	Trustee	January 15, 2013
Heather R. Higgins*
/s/ Barry M. Mandinach	Trustee	January 15, 2013
Barry M. Mandinach*

*Signatures affixed by Lisa R. Price pursuant to Powers of Attorney dated November 22, 2010 and incorporated by reference from Post-Effective Amendment No. 31 to the registration statement of PACE Select Advisors Trust, SEC File No. 33-87254, filed November 28, 2010.

UBS INVESTMENT TRUST

EXHIBIT INDEX

EX-101.INS	XBRL Instance Document
EX-101.SCH	XBRL Taxonomy Extension Schema Document
EX-101.CAL	XBRL Taxonomy Extension Calculation Linkbase
EX-101.DEF	XBRL Taxonomy Extension Definition Linkbase
EX-101.LAB	XBRL Taxonomy Extension Labels Linkbase
EX-101.PRE	XBRL Taxonomy Extension Presentation Linkbase

XML

Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
ProspectusDate	rr_ProspectusDate	Dec. 29, 2012
UBS U.S. Allocation Fund (Prospectus Summary) | UBS U.S. Allocation Fund
Risk Return [Abstract]	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	UBS U.S. Allocation Fund
Objective [Heading]	rr_ObjectiveHeading	Investment objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	Total return, consisting of long-term capital appreciation and current income.
Expense [Heading]	rr_ExpenseHeading	Fees and expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	These tables describe the fees and expenses that you may pay if you buy and hold shares of the fund. You may qualify for sales charge discounts on purchases of Class A shares if you or your family invest, or agree to invest in the future, at least $50,000 in the UBS family of funds. More information about these and other discounts and waivers, as well as eligibility requirements for each share class, is available from your financial advisor and in "Managing your fund account" on page 15 of the prospectus and in "Reduced sales charges, additional purchase, exchange and redemption information and other services" on page 58 of the fund's Statement of Additional Information ("SAI").
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual fund operating expenses (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 150% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	150.00%
Expense Breakpoint Discounts [Text]	rr_ExpenseBreakpointDiscounts	You may qualify for sales charge discounts on purchases of Class A shares if you or your family invest, or agree to invest in the future, at least $50,000 in the UBS family of funds.
Expense Breakpoint, Minimum Investment Required [Amount]	rr_ExpenseBreakpointMinimumInvestmentRequiredAmount	50,000
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the fund for the time periods indicated and then redeem all of your shares at the end of those periods unless otherwise stated. The example also assumes that your investment has a 5% return each year and that the fund's operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading]	rr_StrategyHeading	Principal strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	Principal investments Under normal circumstances, the fund invests at least 80% of its net assets (plus borrowings for investment purposes, if any) in US fixed income and equity securities. The following are the ranges within which the fund, under normal market circumstances, expects to allocate its assets among the various asset classes: (1) US equities-20-90%; (2) investment grade fixed income-0-70%; (3) high yield fixed income-0-15%; and (4) cash equivalents-0-50%. The fund may exceed these ranges and may modify them in the future. Investments in fixed income securities, which are not subject to any credit rating or maturity limitations, may include debt securities of the US government, its agencies and instrumentalities; debt securities of US corporations; and mortgage-backed securities and asset-backed securities. There are different types of US government securities, including those issued or guaranteed by the US government, its agencies and its instrumentalities, and they have different types of government support. Some are supported by the full faith and credit of the US, while others are supported by (1) the ability of the issuer to borrow from the US Treasury; (2) the credit of the issuing agency, instrumentality or government-sponsored entity; (3) pools of assets, such as mortgages; or (4) the US government in some other way.    Investments in equity securities may include dividend-paying securities, common stock and preferred stock. Equity investments may include large, intermediate and small capitalization companies. The fund may, but is not required to, use exchange-traded or over-the-counter derivative instruments for risk management purposes or as part of the fund's investment strategies. The derivatives in which the fund may invest include futures, index options, forward agreements, swap agreements (specifically, total return swaps, interest rate swaps, and credit default swaps), equity participation notes and equity linked notes. All of these derivatives may be used for risk management purposes, such as hedging against a specific security or currency (except with respect to equity participation notes and equity linked notes), or to manage or adjust the risk profile of the fund. In addition, all of the derivative instruments listed above may be used for investment (non-hedging) purposes to earn income; to enhance returns; to replace more traditional direct investments; to obtain exposure to certain markets; or to establish net short positions for individual markets, currencies or securities. Futures on indices and forward agreements may also be used to adjust the fund's portfolio duration. UBS Global Asset Management (Americas) Inc. ("UBS Global AM"), the fund's investment advisor, actively manages the fund. As such, increased portfolio turnover may result in higher levels of brokerage commissions, transaction costs and taxable gains and may therefore adversely affect fund performance. The fund also may invest in other open-end investment companies advised by UBS Global AM in order to pursue its investment objective. The fund pays expenses associated with such investments. Management process The fund is a multi-asset fund and allocates its assets among the major domestic asset classes (US fixed-income, including US high yield (lower-rated) securities, and US equities) based upon UBS Global AM's assessment of prevailing market conditions in the US and abroad. In determining the asset allocation of the fund, UBS Global AM may utilize fundamental valuation and market behavior indicators to construct the fund's portfolio. Within the equity portion of the fund, UBS Global AM may focus on securities whose fundamental values (UBS Global AM's assessment of what a security is worth) it believes are greater than their market prices. UBS Global AM then compares its assessment of a security's value against the prevailing market prices with the aim of constructing a portfolio of stocks with attractive relative price/value characteristics. UBS Global AM's fixed income strategy combines judgments about the absolute value of the fixed income universe and the relative value of issuer sectors, maturity intervals, duration of securities, quality and coupon segments and specific circumstances facing the issuers of fixed income securities. Duration management involves adjusting the sensitivity to interest rates of the holdings. UBS Global AM manages duration by choosing a maturity mix that provides opportunity for appreciation while also limiting interest rate risk.    The fund may invest in cash or cash equivalent instruments, including shares of an affiliated investment company. When market conditions warrant, the fund may make substantial temporary defensive investments in cash equivalents, which may affect its ability to pursue its investment objective.
Risk [Heading]	rr_RiskHeading	Principal risks
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	All investments carry a certain amount of risk and the fund cannot guarantee that it will achieve its investment objective. You may lose money by investing in the fund. An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. The principal risks presented by an investment in the fund are: Asset allocation risk: The risk that the fund may allocate assets to an asset category that underperforms other asset categories. Interest rate risk: An increase in prevailing interest rates typically causes the value of fixed income securities to fall. Changes in interest rates will likely affect the value of longer-duration fixed income securities more than shorter-duration securities and higher quality securities more than lower quality securities. When interest rates are falling, some fixed income securities provide that the issuer may repay them earlier than the maturity date, and if this occurs the fund may have to reinvest these repayments at lower interest rates. Prepayment risk: The fund's mortgage- and asset-backed securities may be prepaid more rapidly than expected, especially when interest rates are falling, and the fund may have to reinvest those prepayments at lower interest rates. When interest rates are rising, slower prepayments may extend the duration of the securities and may reduce their value. Equity risk: Stocks and other equity securities, and securities convertible into stocks, generally fluctuate in value more than bonds. The fund could lose all of its investment in a company's stock. Credit risk: The risk that the fund could lose money if the issuer or guarantor of a fixed income security, or the counterparty to or guarantor of a derivative contract, is unable or unwilling to meet its financial obligations. This risk is likely greater for lower quality investments than for investments that are higher quality. High yield securities ("junk bonds") risk: Lower-rated securities (the issuers of which are typically in poor financial health) are subject to higher risks than investment grade securities. For example, lower-rated securities may be (1) subject to a greater risk of loss of principal and non-payment of interest (including default by the issuer); (2) subject to greater price volatility; and (3) less liquid than investment grade securities. The prices of such securities may be more vulnerable to bad economic news, or even the expectation of bad news, than higher rated fixed income securities.    US Government securities risk: There are different types of US government securities with different levels of credit risk, including the risk of default, depending on the nature of the particular government support for that security. For example, a US government-sponsored entity, such as Federal National Mortgage Association ("Fannie Mae") or Federal Home Loan Mortgage Corporation ("Freddie Mac"), although chartered or sponsored by an Act of Congress, may issue securities that are neither insured nor guaranteed by the US Treasury and are therefore riskier than those that are. Market risk: The risk that the market value of the fund's investments may fluctuate, sometimes rapidly or unpredictably, as the stock and bond markets fluctuate. Market risk may affect a single issuer, industry, or sector of the economy, or it may affect the market as a whole. Moreover, changing market, economic and political conditions in one country or geographic region could adversely impact market, economic and political conditions in other countries or regions. Limited capitalization risk: The risk that securities of smaller capitalization companies tend to be more volatile and less liquid than securities of larger capitalization companies. This can have a disproportionate effect on the market price of smaller capitalization companies and affect the fund's ability to purchase or sell these securities. In general, smaller capitalization companies are more vulnerable than larger companies to adverse business or economic developments and they may have more limited resources. Derivatives risk: The value of "derivatives"-so called because their value "derives" from the value of an underlying asset, reference rate or index-may rise or fall more rapidly than other investments. When using derivatives for non-hedging purposes, it is possible for the fund to lose more than the amount it invested in the derivative. When using derivatives for hedging purposes, the fund's overall returns may be reduced if the hedged investment experiences a favorable price movement. The risks of investing in derivative instruments also include market and management risks. Derivatives relating to fixed income markets are especially susceptible to interest rate risk and credit risk. In addition, many types of swaps and other non-exchange traded derivatives may be subject to liquidity risk, counterparty risk, credit risk and mispricing or valuation complexity. These derivatives risks are different from, and may be greater than, the risks associated with investing directly in securities and other instruments. Risk associated with value investing: Securities selection based on value orientation involves certain risks. Because the prices of value-oriented stocks tend to correlate more closely with economic cycles than growth-oriented stocks, value-oriented stocks generally may be more sensitive to changing economic conditions, such as changes in interest rates, corporate earnings and industrial production. Investment company risk: Investments in open- or closed-end investment companies involve certain risks. The shares of other investment companies are subject to management fees and other expenses of those companies, and the purchase of shares of some investment companies requires the payment of sales loads and (in the case of closed-end investment companies) sometimes substantial premiums above the value of such companies' portfolio securities.    Portfolio turnover risk: The fund may engage in frequent trading, which can result in high portfolio turnover. A high portfolio turnover rate involves greater expenses to the fund, including transaction costs, and is likely to generate more taxable short-term gains for shareholders, which may have an adverse impact on performance. Valuation risk: During periods of reduced market liquidity or in the absence of readily available market quotations the ability of the fund to value the fund's investments becomes more difficult and the judgment of the fund's investment advisor may play a greater role in the valuation of the investments due to reduced availability of reliable objective pricing data. Management risk: The risk that the investment strategies, techniques and risk analyses employed by the investment advisor may not produce the desired results.
Risk Lose Money [Text]	rr_RiskLoseMoney	You may lose money by investing in the fund.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	Risk/return bar chart and table The performance information that follows shows the fund's performance information in a bar chart and an average annual total returns table. The bar chart does not reflect the sales charges of the fund's Class C shares; if it did, the total returns shown would be lower. The information provides some indication of the risks of investing in the fund by showing changes in the fund's performance from year to year and by showing how the fund's average annual total returns compare with those of broad measures of market performance. The UBS U.S. Allocation Fund Index, an unmanaged index compiled by UBS Global AM, shows how the fund's performance compares to an index constructed as follows: from July 22, 1992 (the fund's inception) until February 29, 2004: 100% S&P 500 Index; from March 1, 2004 until May 31, 2005: 65% Russell 3000 Index, 30% Barclays US Aggregate Index, and 5% BofA Merrill Lynch US High Yield Cash Pay Index; and from June 1, 2005 until present: 65% Russell 3000 Index, 30% Barclays US Aggregate Index, and 5% BofA Merrill Lynch US High Yield Cash Pay Constrained Index. The fund's past performance (before and after taxes) is not necessarily an indication of how the fund will perform in the future. This may be particularly true given that part of the bar chart and table reflects the fund's performance during periods when it employed a different investment strategy and had a different portfolio manager (prior to February 15, 2004). Consequently, only a portion of the historical information presented is attributable to the fund's current investment strategy. Updated performance for the fund is available at http://globalam-us.ubs.com/corpweb/performance.do. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. In addition, the after-tax returns shown are not relevant to investors who hold fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. After-tax returns for other classes will vary from the Class C shares' after-tax returns shown. Prior to September 30, 2003, Class C shares were subject to a maximum front-end sales charge of 1.00%; this front end sales charge is not reflected in the average annual total returns table for Class C shares.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The performance information that follows shows the fund's performance information in a bar chart and an average annual total returns table.
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	http://globalam-us.ubs.com/corpweb/performance.do
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The fund's past performance (before and after taxes) is not necessarily an indication of how the fund will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns of Class C Shares
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	The bar chart does not reflect the sales charges of the fund's Class C shares; if it did, the total returns shown would be lower.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Total return January 1 - September 30, 2012: 11.70% Best quarter during calendar years shown-2Q, 2009: 17.27% Worst quarter during calendar years shown-4Q, 2008: (23.66)%
Index No Deduction for Fees, Expenses, Taxes [Text]	rr_IndexNoDeductionForFeesExpensesTaxes	Indices reflect no deduction for fees, expenses or taxes.
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on an investor's tax situation and may differ from those shown. In addition, the after-tax returns shown are not relevant to investors who hold fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns for other classes will vary from the Class C shares' after-tax returns shown.
Caption	rr_AverageAnnualReturnCaption	Average annual total returns (for the periods ended December 31, 2011)
UBS U.S. Allocation Fund (Prospectus Summary) | UBS U.S. Allocation Fund | S&P 500 Index
Risk Return [Abstract]	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	S&P 500 Index
1 Year	rr_AverageAnnualReturnYear01	2.11%
5 Years	rr_AverageAnnualReturnYear05	(0.25%)
10 Years	rr_AverageAnnualReturnYear10	2.92%
UBS U.S. Allocation Fund (Prospectus Summary) | UBS U.S. Allocation Fund | UBS U.S. Allocation Fund Index
Risk Return [Abstract]	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	UBS U.S. Allocation Fund Index (Indices reflect no deduction for fees, expenses or taxes.)
1 Year	rr_AverageAnnualReturnYear01	3.51%
5 Years	rr_AverageAnnualReturnYear05	2.70%
10 Years	rr_AverageAnnualReturnYear10	4.00%
UBS U.S. Allocation Fund (Prospectus Summary) | UBS U.S. Allocation Fund | Class A
Risk Return [Abstract]	rr_RiskReturnAbstract
Maximum front-end sales charge (load) imposed on purchases (as a % of the offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	5.50%
Maximum deferred sales charge (load) (as a % of the lesser of the offering price or the redemption price)	rr_MaximumDeferredSalesChargeOverOfferingPrice	none
Redemption fee (as a % of the amount redeemed within 90 days of purchase, if applicable)	rr_RedemptionFeeOverRedemption	(1.00%)
Exchange fee	rr_ExchangeFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.50%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other expenses	rr_OtherExpensesOverAssets	0.28%
Total annual fund operating expenses	rr_ExpensesOverAssets	1.03%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	649
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	860
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	1,087
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	1,740
Label	rr_AverageAnnualReturnLabel	Class A Return before taxes
1 Year	rr_AverageAnnualReturnYear01	(5.17%)
5 Years	rr_AverageAnnualReturnYear05	(1.71%)
10 Years	rr_AverageAnnualReturnYear10	1.80%
Inception Date	rr_AverageAnnualReturnInceptionDate	May 10, 1993
UBS U.S. Allocation Fund (Prospectus Summary) | UBS U.S. Allocation Fund | Class C
Risk Return [Abstract]	rr_RiskReturnAbstract
Maximum front-end sales charge (load) imposed on purchases (as a % of the offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum deferred sales charge (load) (as a % of the lesser of the offering price or the redemption price)	rr_MaximumDeferredSalesChargeOverOfferingPrice	1.00%
Redemption fee (as a % of the amount redeemed within 90 days of purchase, if applicable)	rr_RedemptionFeeOverRedemption	(1.00%)
Exchange fee	rr_ExchangeFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.50%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other expenses	rr_OtherExpensesOverAssets	0.29%
Total annual fund operating expenses	rr_ExpensesOverAssets	1.79%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	282
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	563
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	970
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	2,150
Expense Example, No Redemption, 1 Year	rr_ExpenseExampleNoRedemptionYear01	182
Expense Example, No Redemption, 3 Years	rr_ExpenseExampleNoRedemptionYear03	563
Expense Example, No Redemption, 5 Years	rr_ExpenseExampleNoRedemptionYear05	970
Expense Example, No Redemption, 10 Years	rr_ExpenseExampleNoRedemptionYear10	2,150
Annual Return 2002	rr_AnnualReturn2002	(23.46%)
Annual Return 2003	rr_AnnualReturn2003	26.52%
Annual Return 2004	rr_AnnualReturn2004	11.00%
Annual Return 2005	rr_AnnualReturn2005	5.78%
Annual Return 2006	rr_AnnualReturn2006	10.39%
Annual Return 2007	rr_AnnualReturn2007	1.54%
Annual Return 2008	rr_AnnualReturn2008	(36.60%)
Annual Return 2009	rr_AnnualReturn2009	29.64%
Annual Return 2010	rr_AnnualReturn2010	12.50%
Annual Return 2011	rr_AnnualReturn2011	(0.39%)
Year to Date Return, Label	rr_YearToDateReturnLabel	Total return January 1 - September 30, 2012:
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Sep. 30, 2012
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	11.70%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best quarter during calendar years shown-2Q, 2009:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	17.27%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst quarter during calendar years shown-4Q, 2008:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(23.66%)
Label	rr_AverageAnnualReturnLabel	Class C Return before taxes
1 Year	rr_AverageAnnualReturnYear01	(1.39%)
5 Years	rr_AverageAnnualReturnYear05	(1.33%)
10 Years	rr_AverageAnnualReturnYear10	1.62%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 22, 1992
UBS U.S. Allocation Fund (Prospectus Summary) | UBS U.S. Allocation Fund | Class C | After Taxes on Distributions
Risk Return [Abstract]	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Class C Return after taxes on distributions
1 Year	rr_AverageAnnualReturnYear01	(1.42%)
5 Years	rr_AverageAnnualReturnYear05	(1.70%)
10 Years	rr_AverageAnnualReturnYear10	1.34%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 22, 1992
UBS U.S. Allocation Fund (Prospectus Summary) | UBS U.S. Allocation Fund | Class C | After Taxes on Distributions and Sales
Risk Return [Abstract]	rr_RiskReturnAbstract
Label	rr_AverageAnnualReturnLabel	Class C Return after taxes on distributions and sale of fund shares
1 Year	rr_AverageAnnualReturnYear01	(0.85%)
5 Years	rr_AverageAnnualReturnYear05	(1.31%)
10 Years	rr_AverageAnnualReturnYear10	1.27%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jul. 22, 1992
UBS U.S. Allocation Fund (Prospectus Summary) | UBS U.S. Allocation Fund | Class Y
Risk Return [Abstract]	rr_RiskReturnAbstract
Maximum front-end sales charge (load) imposed on purchases (as a % of the offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum deferred sales charge (load) (as a % of the lesser of the offering price or the redemption price)	rr_MaximumDeferredSalesChargeOverOfferingPrice	none
Redemption fee (as a % of the amount redeemed within 90 days of purchase, if applicable)	rr_RedemptionFeeOverRedemption	(1.00%)
Exchange fee	rr_ExchangeFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.50%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	none
Other expenses	rr_OtherExpensesOverAssets	0.25%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.75%
Expense Example, with Redemption, 1 Year	rr_ExpenseExampleYear01	77
Expense Example, with Redemption, 3 Years	rr_ExpenseExampleYear03	240
Expense Example, with Redemption, 5 Years	rr_ExpenseExampleYear05	417
Expense Example, with Redemption, 10 Years	rr_ExpenseExampleYear10	930
Label	rr_AverageAnnualReturnLabel	Class Y Return before taxes
1 Year	rr_AverageAnnualReturnYear01	0.62%
5 Years	rr_AverageAnnualReturnYear05	(0.26%)
10 Years	rr_AverageAnnualReturnYear10	2.73%
Inception Date	rr_AverageAnnualReturnInceptionDate	May 10, 1993

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UBS U.S. Allocation Fund (Prospectus Summary) | UBS U.S. Allocation Fund

UBS U.S. Allocation Fund

Investment objective

Total return, consisting of long-term capital appreciation and current income.

Fees and expenses

These tables describe the fees and expenses that you may pay if you buy and hold
shares of the fund. You may qualify for sales charge discounts on purchases of
Class A shares if you or your family invest, or agree to invest in the future,
at least $50,000 in the UBS family of funds. More information about these and
other discounts and waivers, as well as eligibility requirements for each share
class, is available from your financial advisor and in "Managing your fund
account" on page 15 of the prospectus and in "Reduced sales charges, additional
purchase, exchange and redemption information and other services" on page 58 of
the fund's Statement of Additional Information ("SAI").

Shareholder fees (fees paid directly from your investment)

Shareholder Fees UBS U.S. Allocation Fund	Class A	Class C	Class Y
Maximum front-end sales charge (load) imposed on purchases (as a % of the offering price)	5.50%	none	none
Maximum deferred sales charge (load) (as a % of the lesser of the offering price or the redemption price)	none	1.00%	none
Redemption fee (as a % of the amount redeemed within 90 days of purchase, if applicable)	1.00%	1.00%	1.00%
Exchange fee	none	none	none

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

Annual Fund Operating Expenses UBS U.S. Allocation Fund	Class A	Class C	Class Y
Management fees	0.50%	0.50%	0.50%
Distribution and/or service (12b-1) fees	0.25%	1.00%	none
Other expenses	0.28%	0.29%	0.25%
Total annual fund operating expenses	1.03%	1.79%	0.75%

Example

This example is intended to help you compare the cost of investing in the fund
with the cost of investing in other mutual funds. The example assumes that you
invest $10,000 in the fund for the time periods indicated and then redeem all
of your shares at the end of those periods unless otherwise stated. The example
also assumes that your investment has a 5% return each year and that the fund's
operating expenses remain the same.

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

Expense Example UBS U.S. Allocation Fund (USD $)	Expense Example, with Redemption, 1 Year	Expense Example, with Redemption, 3 Years	Expense Example, with Redemption, 5 Years	Expense Example, with Redemption, 10 Years
Class A	649	860	1,087	1,740
Class C	282	563	970	2,150
Class Y	77	240	417	930

Expense Example, No Redemption (USD $)	Expense Example, No Redemption, 1 Year	Expense Example, No Redemption, 3 Years	Expense Example, No Redemption, 5 Years	Expense Example, No Redemption, 10 Years
UBS U.S. Allocation Fund Class C	182	563	970	2,150

Portfolio turnover

The fund pays transaction costs, such as commissions, when it buys and sells
securities (or "turns over" its portfolio). A higher portfolio turnover rate may
indicate higher transaction costs and may result in higher taxes when fund
shares are held in a taxable account. These costs, which are not reflected in
annual fund operating expenses or in the example, affect the fund's performance.
During the most recent fiscal year, the fund's portfolio turnover rate was 150%
of the average value of its portfolio.

Principal strategies

Principal investments
Under normal circumstances, the fund invests at least 80% of its net assets
(plus borrowings for investment purposes, if any) in US fixed income and equity
securities. The following are the ranges within which the fund, under normal
market circumstances, expects to allocate its assets among the various asset
classes: (1) US equities-20-90%; (2) investment grade fixed income-0-70%; (3)
high yield fixed income-0-15%; and (4) cash equivalents-0-50%. The fund may
exceed these ranges and may modify them in the future.

Investments in fixed income securities, which are not subject to any credit
rating or maturity limitations, may include debt securities of the US government,
its agencies and instrumentalities; debt securities of US corporations; and
mortgage-backed securities and asset-backed securities. There are different
types of US government securities, including those issued or guaranteed by
the US government, its agencies and its instrumentalities, and they have
different types of government support. Some are supported by the full faith
and credit of the US, while others are supported by (1) the ability of the
issuer to borrow from the US Treasury; (2) the credit of the issuing agency,
instrumentality or government-sponsored entity; (3) pools of assets, such as
mortgages; or (4) the US government in some other way.
  
Investments in equity securities may include dividend-paying securities, common
stock and preferred stock. Equity investments may include large, intermediate
and small capitalization companies.

The fund may, but is not required to, use exchange-traded or over-the-counter
derivative instruments for risk management purposes or as part of the fund's
investment strategies. The derivatives in which the fund may invest include
futures, index options, forward agreements, swap agreements (specifically, total
return swaps, interest rate swaps, and credit default swaps), equity participation
notes and equity linked notes. All of these derivatives may be used for risk
management purposes, such as hedging against a specific security or currency
(except with respect to equity participation notes and equity linked notes), or
to manage or adjust the risk profile of the fund. In addition, all of the
derivative instruments listed above may be used for investment (non-hedging)
purposes to earn income; to enhance returns; to replace more traditional direct
investments; to obtain exposure to certain markets; or to establish net short
positions for individual markets, currencies or securities. Futures on indices
and forward agreements may also be used to adjust the fund's portfolio duration.

UBS Global Asset Management (Americas) Inc. ("UBS Global AM"), the fund's
investment advisor, actively manages the fund. As such, increased portfolio
turnover may result in higher levels of brokerage commissions, transaction costs
and taxable gains and may therefore adversely affect fund performance. The fund
also may invest in other open-end investment companies advised by UBS Global AM
in order to pursue its investment objective. The fund pays expenses associated
with such investments.

Management process
The fund is a multi-asset fund and allocates its assets among the major domestic
asset classes (US fixed-income, including US high yield (lower-rated) securities,
and US equities) based upon UBS Global AM's assessment of prevailing market
conditions in the US and abroad. In determining the asset allocation of the fund,
UBS Global AM may utilize fundamental valuation and market behavior indicators to
construct the fund's portfolio.

Within the equity portion of the fund, UBS Global AM may focus on securities
whose fundamental values (UBS Global AM's assessment of what a security is
worth) it believes are greater than their market prices. UBS Global AM then
compares its assessment of a security's value against the prevailing market
prices with the aim of constructing a portfolio of stocks with attractive
relative price/value characteristics.

UBS Global AM's fixed income strategy combines judgments about the absolute
value of the fixed income universe and the relative value of issuer sectors,
maturity intervals, duration of securities, quality and coupon segments and
specific circumstances facing the issuers of fixed income securities. Duration
management involves adjusting the sensitivity to interest rates of the holdings.
UBS Global AM manages duration by choosing a maturity mix that provides
opportunity for appreciation while also limiting interest rate risk.
  
The fund may invest in cash or cash equivalent instruments, including shares of
an affiliated investment company. When market conditions warrant, the fund may
make substantial temporary defensive investments in cash equivalents, which may
affect its ability to pursue its investment objective.

Principal risks

All investments carry a certain amount of risk and the fund cannot guarantee
that it will achieve its investment objective. You may lose money by investing
in the fund. An investment in the fund is not a bank deposit and is not insured
or guaranteed by the Federal Deposit Insurance Corporation or any other
government agency. The principal risks presented by an investment in the fund
are:

Asset allocation risk: The risk that the fund may allocate assets to an asset
category that underperforms other asset categories.

Interest rate risk: An increase in prevailing interest rates typically causes
the value of fixed income securities to fall. Changes in interest rates will
likely affect the value of longer-duration fixed income securities more than
shorter-duration securities and higher quality securities more than lower
quality securities. When interest rates are falling, some fixed income
securities provide that the issuer may repay them earlier than the maturity
date, and if this occurs the fund may have to reinvest these repayments at lower
interest rates.

Prepayment risk: The fund's mortgage- and asset-backed securities may be prepaid
more rapidly than expected, especially when interest rates are falling, and the
fund may have to reinvest those prepayments at lower interest rates. When
interest rates are rising, slower prepayments may extend the duration of the
securities and may reduce their value.

Equity risk: Stocks and other equity securities, and securities convertible into
stocks, generally fluctuate in value more than bonds. The fund could lose all of
its investment in a company's stock.

Credit risk: The risk that the fund could lose money if the issuer or guarantor
of a fixed income security, or the counterparty to or guarantor of a derivative
contract, is unable or unwilling to meet its financial obligations. This risk is
likely greater for lower quality investments than for investments that are
higher quality.

High yield securities ("junk bonds") risk: Lower-rated securities (the issuers
of which are typically in poor financial health) are subject to higher risks
than investment grade securities. For example, lower-rated securities may be (1)
subject to a greater risk of loss of principal and non-payment of interest
(including default by the issuer); (2) subject to greater price volatility; and
(3) less liquid than investment grade securities. The prices of such securities
may be more vulnerable to bad economic news, or even the expectation of bad
news, than higher rated fixed income securities.
  
US Government securities risk: There are different types of US government
securities with different levels of credit risk, including the risk of default,
depending on the nature of the particular government support for that security.
For example, a US government-sponsored entity, such as Federal National Mortgage
Association ("Fannie Mae") or Federal Home Loan Mortgage Corporation ("Freddie
Mac"), although chartered or sponsored by an Act of Congress, may issue
securities that are neither insured nor guaranteed by the US Treasury and are
therefore riskier than those that are.

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

Limited capitalization risk: The risk that securities of smaller capitalization
companies tend to be more volatile and less liquid than securities of larger
capitalization companies. This can have a disproportionate effect on the market
price of smaller capitalization companies and affect the fund's ability to
purchase or sell these securities. In general, smaller capitalization companies
are more vulnerable than larger companies to adverse business or economic
developments and they may have more limited resources.

Derivatives risk: The value of "derivatives"-so called because their value
"derives" from the value of an underlying asset, reference rate or index-may
rise or fall more rapidly than other investments. When using derivatives for
non-hedging purposes, it is possible for the fund to lose more than the amount
it invested in the derivative. When using derivatives for hedging purposes,
the fund's overall returns may be reduced if the hedged investment experiences a
favorable price movement. The risks of investing in derivative instruments also
include market and management risks. Derivatives relating to fixed income
markets are especially susceptible to interest rate risk and credit risk. In
addition, many types of swaps and other non-exchange traded derivatives may be
subject to liquidity risk, counterparty risk, credit risk and mispricing or
valuation complexity. These derivatives risks are different from, and may be
greater than, the risks associated with investing directly in securities and
other instruments.

Risk associated with value investing: Securities selection based on value
orientation involves certain risks. Because the prices of value-oriented stocks
tend to correlate more closely with economic cycles than growth-oriented stocks,
value-oriented stocks generally may be more sensitive to changing economic
conditions, such as changes in interest rates, corporate earnings and industrial
production.

Investment company risk: Investments in open- or closed-end investment companies
involve certain risks. The shares of other investment companies are subject to
management fees and other expenses of those companies, and the purchase of
shares of some investment companies requires the payment of sales loads and (in
the case of closed-end investment companies) sometimes substantial premiums
above the value of such companies' portfolio securities.
  
Portfolio turnover risk: The fund may engage in frequent trading, which can
result in high portfolio turnover. A high portfolio turnover rate involves
greater expenses to the fund, including transaction costs, and is likely to
generate more taxable short-term gains for shareholders, which may have an
adverse impact on performance.

Valuation risk: During periods of reduced market liquidity or in the absence of
readily available market quotations the ability of the fund to value the fund's
investments becomes more difficult and the judgment of the fund's investment
advisor may play a greater role in the valuation of the investments due to
reduced availability of reliable objective pricing data.

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

Performance

Risk/return bar chart and table
The performance information that follows shows the fund's performance
information in a bar chart and an average annual total returns table. The bar
chart does not reflect the sales charges of the fund's Class C shares; if it
did, the total returns shown would be lower. The information provides some
indication of the risks of investing in the fund by showing changes in the
fund's performance from year to year and by showing how the fund's average
annual total returns compare with those of broad measures of market performance.
The UBS U.S. Allocation Fund Index, an unmanaged index compiled by UBS Global
AM, shows how the fund's performance compares to an index constructed as
follows: from July 22, 1992 (the fund's inception) until February 29, 2004: 100%
S&P 500 Index; from March 1, 2004 until May 31, 2005: 65% Russell 3000 Index,
30% Barclays US Aggregate Index, and 5% BofA Merrill Lynch US High Yield Cash
Pay Index; and from June 1, 2005 until present: 65% Russell 3000 Index, 30%
Barclays US Aggregate Index, and 5% BofA Merrill Lynch US High Yield Cash Pay
Constrained Index. The fund's past performance (before and after taxes) is not
necessarily an indication of how the fund will perform in the future. This may
be particularly true given that part of the bar chart and table reflects the
fund's performance during periods when it employed a different investment
strategy and had a different portfolio manager (prior to February 15, 2004).
Consequently, only a portion of the historical information presented is
attributable to the fund's current investment strategy. Updated performance for
the fund is available at http://globalam-us.ubs.com/corpweb/performance.do.

After-tax returns are calculated using the historical highest individual federal
marginal income tax rates and do not reflect the impact of state and local
taxes. Actual after-tax returns depend on an investor's tax situation and may
differ from those shown. In addition, the after-tax returns shown are not
relevant to investors who hold fund shares through tax-deferred arrangements,
such as 401(k) plans or individual retirement accounts. After-tax returns for
other classes will vary from the Class C shares' after-tax returns shown. Prior
to September 30, 2003, Class C shares were subject to a maximum front-end sales
charge of 1.00%; this front end sales charge is not reflected in the average
annual total returns table for Class C shares.

Annual Total Returns of Class C Shares

Total return January 1 - September 30, 2012: 11.70%
Best quarter during calendar years shown-2Q, 2009: 17.27%
Worst quarter during calendar years shown-4Q, 2008: (23.66)%

Average annual total returns (for the periods ended December 31, 2011)

Average Annual Total Returns UBS U.S. Allocation Fund	Label	1 Year	5 Years	10 Years	Inception Date
Class A	Class A Return before taxes	(5.17%)	(1.71%)	1.80%	May 10, 1993
Class C	Class C Return before taxes	(1.39%)	(1.33%)	1.62%	Jul. 22, 1992
Class C After Taxes on Distributions	Class C Return after taxes on distributions	(1.42%)	(1.70%)	1.34%	Jul. 22, 1992
Class C After Taxes on Distributions and Sales	Class C Return after taxes on distributions and sale of fund shares	(0.85%)	(1.31%)	1.27%	Jul. 22, 1992
Class Y	Class Y Return before taxes	0.62%	(0.26%)	2.73%	May 10, 1993
S&P 500 Index	S&P 500 Index	2.11%	(0.25%)	2.92%
UBS U.S. Allocation Fund Index	UBS U.S. Allocation Fund Index (Indices reflect no deduction for fees, expenses or taxes.)	3.51%	2.70%	4.00%

XML

Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
Document Type	dei_DocumentType	485BPOS
Document Period End Date	dei_DocumentPeriodEndDate	Aug. 31, 2012
Registrant Name	dei_EntityRegistrantName	UBS INVESTMENT TRUST
Central Index Key	dei_EntityCentralIndexKey	0000873803
Amendment Flag	dei_AmendmentFlag	false
Document Creation Date	dei_DocumentCreationDate	Dec. 28, 2012
Document Effective Date	dei_DocumentEffectiveDate	Dec. 29, 2012
UBS U.S. Allocation Fund (Prospectus Summary) | UBS U.S. Allocation Fund | Class A
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	PWTAX
UBS U.S. Allocation Fund (Prospectus Summary) | UBS U.S. Allocation Fund | Class C
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	KPAAX
UBS U.S. Allocation Fund (Prospectus Summary) | UBS U.S. Allocation Fund | Class Y
Risk Return [Abstract]	rr_RiskReturnAbstract
Trading Symbol	dei_TradingSymbol	PWTYX