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        <numAddedClass>0</numAddedClass>
        <numTerminatedClass>0</numTerminatedClass>
        <sharesOutstandings>
          <sharesOutstanding sharesOutstandingClassName="UBS Liquid Assets Government Fund" sharesOutstandingClassId="C000007336" sharesOutstandingTickerSymbol="N/A"/>
        </sharesOutstandings>
        <fundTypes>
          <fundType>Money Market Fund</fundType>
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        <isNonDiversifiedCompany>N</isNonDiversifiedCompany>
        <isForeignSubsidiary>N</isForeignSubsidiary>
        <isFundSecuritiesLending>N</isFundSecuritiesLending>
        <didFundLendSecurities>N</didFundLendSecurities>
        <paymentToAgentManagerType>N/A</paymentToAgentManagerType>
        <avgPortfolioSecuritiesValue>N/A</avgPortfolioSecuritiesValue>
        <netIncomeSecuritiesLending>N/A</netIncomeSecuritiesLending>
        <relyOnRuleTypes>
          <relyOnRuleType>Rule 32a-4 (17 CFR 270.32a-4)</relyOnRuleType>
        </relyOnRuleTypes>
        <isExpenseLimitationInPlace>Y</isExpenseLimitationInPlace>
        <isExpenseReducedOrWaived>Y</isExpenseReducedOrWaived>
        <isFeesWaivedRecoupable>N</isFeesWaivedRecoupable>
        <isExpenseWaivedRecoupable>N</isExpenseWaivedRecoupable>
        <investmentAdvisers>
          <investmentAdviser>
            <investmentAdviserName>UBS Asset Management (Americas) LLC</investmentAdviserName>
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            <investmentAdviserLei>F88SLSBEMHN5FUSNRO91</investmentAdviserLei>
            <investmentAdviserStateCountry investmentAdviserState="US-IL" investmentAdviserCountry="US"/>
            <isInvestmentAdviserHired>N</isInvestmentAdviserHired>
          </investmentAdviser>
        </investmentAdvisers>
        <transferAgents>
          <transferAgent>
            <transferAgentName>BNY Mellon Investment Servicing (US) Inc.</transferAgentName>
            <transferAgentFileNo>084-01761</transferAgentFileNo>
            <transferAgentLei>549300CFZQLI9QMJ1Z03</transferAgentLei>
            <transferAgentStateCountry transferAgentState="US-DE" transferAgentCountry="US"/>
            <isTransferAgentAffiliated>N</isTransferAgentAffiliated>
            <isTransferAgentSubAgent>N</isTransferAgentSubAgent>
          </transferAgent>
        </transferAgents>
        <isTransferAgentHiredOrTerminated>N</isTransferAgentHiredOrTerminated>
        <pricingServices>
          <pricingService>
            <pricingServiceName>JPMorgan Chase Bank, National Association</pricingServiceName>
            <pricingServiceLei>7H6GLXDRUGQFU57RNE97</pricingServiceLei>
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            <isPricingServiceAffiliated>N</isPricingServiceAffiliated>
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          <pricingService>
            <pricingServiceName>S&amp;P Global Inc.</pricingServiceName>
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          <pricingService>
            <pricingServiceName>London Stock Exchange Group PLC</pricingServiceName>
            <pricingServiceLei>213800QAUUUP6I445N30</pricingServiceLei>
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        </pricingServices>
        <isPricingServiceHiredOrTerminated>Y</isPricingServiceHiredOrTerminated>
        <custodians>
          <custodian>
            <custodianName>State Street Bank and Trust Company</custodianName>
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            <isSubCustodian>N</isSubCustodian>
            <custodyType>Bank - section 17(f)(1) (15 U.S.C. 80a-17(f)(1))</custodyType>
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          <custodian>
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            <custodianCountry>BE</custodianCountry>
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            <isSubCustodian>Y</isSubCustodian>
            <custodyType>Foreign securities depository - rule 17f-7 (17 CFR 270.17f-7)</custodyType>
          </custodian>
        </custodians>
        <isCustodianHiredOrTerminated>N</isCustodianHiredOrTerminated>
        <shareholderServicingAgents>
          <shareholderServicingAgent>
            <shareholderServiceAgentName>BNY Mellon Investment Servicing (US) Inc.</shareholderServiceAgentName>
            <shareholderServiceAgentLei>549300CFZQLI9QMJ1Z03</shareholderServiceAgentLei>
            <shareholderServiceAgentStateCountry shareholderServiceAgentState="US-DE" shareholderServiceAgentCountry="US"/>
            <isShareholderServiceAgentAffiliated>N</isShareholderServiceAgentAffiliated>
            <isShareholderServiceAgentSubshare>N</isShareholderServiceAgentSubshare>
          </shareholderServicingAgent>
        </shareholderServicingAgents>
        <isShareholderServiceHiredTerminated>N</isShareholderServiceHiredTerminated>
        <admins>
          <admin>
            <adminName>UBS Asset Management (Americas) LLC</adminName>
            <adminLei>F88SLSBEMHN5FUSNRO91</adminLei>
            <adminStateCountry adminState="US-IL" adminCountry="US"/>
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            <isAdminSubAdmin>N</isAdminSubAdmin>
          </admin>
        </admins>
        <isAdminHiredOrTerminated>N</isAdminHiredOrTerminated>
        <brokerDealers>
          <brokerDealer>
            <brokerDealerName>UBS Securities LLC</brokerDealerName>
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            <brokerDealerStateCountry brokerDealerState="US-NY" brokerDealerCountry="US"/>
            <brokerDealerCommission>0.00000000</brokerDealerCommission>
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        </brokerDealers>
        <aggregateCommission>0.00000000</aggregateCommission>
        <principalTransactions>
          <principalTransaction>
            <principalName>Barclays Capital Inc.</principalName>
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            <principalLei>AC28XWWI3WIBK2824319</principalLei>
            <principalStateCountry principalState="US-NY" principalCountry="US"/>
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          </principalTransaction>
          <principalTransaction>
            <principalName>Loop Capital Markets LLC</principalName>
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            <principalLei>254900FPPM2WN90D4786</principalLei>
            <principalStateCountry principalState="US-IL" principalCountry="US"/>
            <principalTotalPurchaseSale>10906093.61000000</principalTotalPurchaseSale>
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          <principalTransaction>
            <principalName>J.P. Morgan Securities LLC</principalName>
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          <principalTransaction>
            <principalName>BMO Capital Markets Corp.</principalName>
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          <principalTransaction>
            <principalName>Goldman Sachs &amp; Co. LLC</principalName>
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          <principalTransaction>
            <principalName>MUFG Securities Americas Inc.</principalName>
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            <principalLei>K5HU16E3LMSVCCJJJ255</principalLei>
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            <principalTotalPurchaseSale>54950000000.00000000</principalTotalPurchaseSale>
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          <principalTransaction>
            <principalName>State Street Bank and Trust Company</principalName>
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            <principalLei>571474TGEMMWANRLN572</principalLei>
            <principalStateCountry principalState="US-MA" principalCountry="US"/>
            <principalTotalPurchaseSale>109976367000.00000000</principalTotalPurchaseSale>
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          <principalTransaction>
            <principalName>BNY Capital Markets, LLC</principalName>
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          <principalTransaction>
            <principalName>Citadel Securities LLC</principalName>
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            <principalCrdNo>000116797</principalCrdNo>
            <principalLei>12UUJYTN7D3SW8KCSG25</principalLei>
            <principalStateCountry principalState="US-FL" principalCountry="US"/>
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          <principalTransaction>
            <principalName>Daiwa Capital Markets America Inc.</principalName>
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        <principalAggregatePurchase>166589608588.60000000</principalAggregatePurchase>
        <isBrokerageResearchPayment>N</isBrokerageResearchPayment>
        <dailyAvgNetAssets>1070035100.38989041</dailyAvgNetAssets>
        <hasLineOfCredit>N</hasLineOfCredit>
        <isInterfundLending>N</isInterfundLending>
        <isInterfundBorrowing>N</isInterfundBorrowing>
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      <managementInvestmentQuestion>
        <mgmtInvFundName>UBS RMA Government Money Market Fund</mgmtInvFundName>
        <mgmtInvSeriesId>S000053134</mgmtInvSeriesId>
        <mgmtInvLei>549300WUNTYEEH9XHV55</mgmtInvLei>
        <isFirstFilingByFund>N</isFirstFilingByFund>
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        <numTerminatedClass>0</numTerminatedClass>
        <sharesOutstandings>
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        <isFundSecuritiesLending>N</isFundSecuritiesLending>
        <didFundLendSecurities>N</didFundLendSecurities>
        <paymentToAgentManagerType>N/A</paymentToAgentManagerType>
        <avgPortfolioSecuritiesValue>N/A</avgPortfolioSecuritiesValue>
        <netIncomeSecuritiesLending>N/A</netIncomeSecuritiesLending>
        <relyOnRuleTypes>
          <relyOnRuleType>Rule 17a-8 (17 CFR 270.17a-8)</relyOnRuleType>
          <relyOnRuleType>Rule 32a-4 (17 CFR 270.32a-4)</relyOnRuleType>
        </relyOnRuleTypes>
        <isExpenseLimitationInPlace>Y</isExpenseLimitationInPlace>
        <isExpenseReducedOrWaived>N</isExpenseReducedOrWaived>
        <isFeesWaivedRecoupable>N</isFeesWaivedRecoupable>
        <isExpenseWaivedRecoupable>N</isExpenseWaivedRecoupable>
        <investmentAdvisers>
          <investmentAdviser>
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            <investmentAdviserLei>F88SLSBEMHN5FUSNRO91</investmentAdviserLei>
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            <isInvestmentAdviserHired>N</isInvestmentAdviserHired>
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        <transferAgents>
          <transferAgent>
            <transferAgentName>BNY Mellon Investment Servicing (US) Inc.</transferAgentName>
            <transferAgentFileNo>084-01761</transferAgentFileNo>
            <transferAgentLei>549300CFZQLI9QMJ1Z03</transferAgentLei>
            <transferAgentStateCountry transferAgentState="US-DE" transferAgentCountry="US"/>
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            <isTransferAgentSubAgent>N</isTransferAgentSubAgent>
          </transferAgent>
        </transferAgents>
        <isTransferAgentHiredOrTerminated>N</isTransferAgentHiredOrTerminated>
        <pricingServices>
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            <pricingServiceName>S&amp;P Global Inc.</pricingServiceName>
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          <pricingService>
            <pricingServiceName>London Stock Exchange Group PLC</pricingServiceName>
            <pricingServiceLei>213800QAUUUP6I445N30</pricingServiceLei>
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            <pricingServiceName>JPMorgan Chase Bank, National Association</pricingServiceName>
            <pricingServiceLei>7H6GLXDRUGQFU57RNE97</pricingServiceLei>
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        <isPricingServiceHiredOrTerminated>Y</isPricingServiceHiredOrTerminated>
        <custodians>
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            <isShareholderServiceAgentSubshare>N</isShareholderServiceAgentSubshare>
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        </shareholderServicingAgents>
        <isShareholderServiceHiredTerminated>N</isShareholderServiceHiredTerminated>
        <admins>
          <admin>
            <adminName>UBS Asset Management (Americas) LLC</adminName>
            <adminLei>F88SLSBEMHN5FUSNRO91</adminLei>
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        <isAdminHiredOrTerminated>N</isAdminHiredOrTerminated>
        <brokerDealers>
          <brokerDealer>
            <brokerDealerName>UBS Securities LLC</brokerDealerName>
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            <brokerDealerLei>T6FIZBDPKLYJKFCRVK44</brokerDealerLei>
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        <dailyAvgNetAssets>905607308.11052054</dailyAvgNetAssets>
        <hasLineOfCredit>N</hasLineOfCredit>
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      <managementInvestmentQuestion>
        <mgmtInvFundName>UBS Prime Preferred Fund</mgmtInvFundName>
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        <sharesOutstandings>
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        <fundTypes>
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          <masterFeederFundInfo fundType="Master-Feeder Fund">
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        <isFundSecuritiesLending>N</isFundSecuritiesLending>
        <didFundLendSecurities>N</didFundLendSecurities>
        <paymentToAgentManagerType>N/A</paymentToAgentManagerType>
        <avgPortfolioSecuritiesValue>N/A</avgPortfolioSecuritiesValue>
        <netIncomeSecuritiesLending>N/A</netIncomeSecuritiesLending>
        <relyOnRuleTypes>
          <relyOnRuleType>Rule 32a-4 (17 CFR 270.32a-4)</relyOnRuleType>
          <relyOnRuleType>Rule 17a-8 (17 CFR 270.17a-8)</relyOnRuleType>
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        <isExpenseLimitationInPlace>Y</isExpenseLimitationInPlace>
        <isExpenseReducedOrWaived>Y</isExpenseReducedOrWaived>
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        <isExpenseWaivedRecoupable>N</isExpenseWaivedRecoupable>
        <investmentAdvisers>
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            <isInvestmentAdviserHired>N</isInvestmentAdviserHired>
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        <transferAgents>
          <transferAgent>
            <transferAgentName>BNY Mellon Investment Servicing (US) Inc.</transferAgentName>
            <transferAgentFileNo>084-01761</transferAgentFileNo>
            <transferAgentLei>549300CFZQLI9QMJ1Z03</transferAgentLei>
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            <isTransferAgentSubAgent>N</isTransferAgentSubAgent>
          </transferAgent>
        </transferAgents>
        <isTransferAgentHiredOrTerminated>N</isTransferAgentHiredOrTerminated>
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          <pricingService>
            <pricingServiceName>London Stock Exchange Group PLC</pricingServiceName>
            <pricingServiceLei>213800QAUUUP6I445N30</pricingServiceLei>
            <pricingServiceCountry>GB</pricingServiceCountry>
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          <pricingService>
            <pricingServiceName>JPMorgan Chase Bank, National Association</pricingServiceName>
            <pricingServiceLei>7H6GLXDRUGQFU57RNE97</pricingServiceLei>
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            <pricingServiceName>S&amp;P Global Inc.</pricingServiceName>
            <pricingServiceLei>Y6X4K52KMJMZE7I7MY94</pricingServiceLei>
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        <isPricingServiceHiredOrTerminated>Y</isPricingServiceHiredOrTerminated>
        <custodians>
          <custodian>
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            <custodyType>Bank - section 17(f)(1) (15 U.S.C. 80a-17(f)(1))</custodyType>
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          <shareholderServicingAgent>
            <shareholderServiceAgentName>BNY Mellon Investment Servicing (US) Inc.</shareholderServiceAgentName>
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            <isShareholderServiceAgentSubshare>N</isShareholderServiceAgentSubshare>
          </shareholderServicingAgent>
        </shareholderServicingAgents>
        <isShareholderServiceHiredTerminated>N</isShareholderServiceHiredTerminated>
        <admins>
          <admin>
            <adminName>UBS Asset Management (Americas) LLC</adminName>
            <adminLei>F88SLSBEMHN5FUSNRO91</adminLei>
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            <isAdminAffiliated>Y</isAdminAffiliated>
            <isAdminSubAdmin>N</isAdminSubAdmin>
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        </admins>
        <isAdminHiredOrTerminated>N</isAdminHiredOrTerminated>
        <brokerDealers>
          <brokerDealer>
            <brokerDealerName>UBS Securities LLC</brokerDealerName>
            <brokerDealerFileNo>8-22651</brokerDealerFileNo>
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      <managementInvestmentQuestion>
        <mgmtInvFundName>UBS Select Treasury Preferred Fund</mgmtInvFundName>
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        <didFundLendSecurities>N</didFundLendSecurities>
        <paymentToAgentManagerType>N/A</paymentToAgentManagerType>
        <avgPortfolioSecuritiesValue>N/A</avgPortfolioSecuritiesValue>
        <netIncomeSecuritiesLending>N/A</netIncomeSecuritiesLending>
        <relyOnRuleTypes>
          <relyOnRuleType>Rule 32a-4 (17 CFR 270.32a-4)</relyOnRuleType>
          <relyOnRuleType>Rule 17a-8 (17 CFR 270.17a-8)</relyOnRuleType>
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        <isExpenseWaivedRecoupable>N</isExpenseWaivedRecoupable>
        <investmentAdvisers>
          <investmentAdviser>
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        <transferAgents>
          <transferAgent>
            <transferAgentName>BNY Mellon Investment Servicing (US) Inc.</transferAgentName>
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        <isTransferAgentHiredOrTerminated>N</isTransferAgentHiredOrTerminated>
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          <pricingService>
            <pricingServiceName>London Stock Exchange Group PLC</pricingServiceName>
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            <pricingServiceName>JPMorgan Chase Bank, National Association</pricingServiceName>
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            <adminName>UBS Asset Management (Americas) LLC</adminName>
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            <brokerDealerName>UBS Securities LLC</brokerDealerName>
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      <managementInvestmentQuestion>
        <mgmtInvFundName>UBS Select 100% US Treasury Preferred Fund</mgmtInvFundName>
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        <sharesOutstandings>
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          <sharesOutstanding sharesOutstandingClassName="Class P" sharesOutstandingClassId="C000248580" sharesOutstandingTickerSymbol="STAXX"/>
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        <paymentToAgentManagerType>N/A</paymentToAgentManagerType>
        <avgPortfolioSecuritiesValue>N/A</avgPortfolioSecuritiesValue>
        <netIncomeSecuritiesLending>N/A</netIncomeSecuritiesLending>
        <relyOnRuleTypes>
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        <isExpenseWaivedRecoupable>N</isExpenseWaivedRecoupable>
        <investmentAdvisers>
          <investmentAdviser>
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        <transferAgents>
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          <pricingService>
            <pricingServiceName>JPMorgan Chase Bank, National Association</pricingServiceName>
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        <mgmtInvFundName>UBS Prime Reserves Fund</mgmtInvFundName>
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        <isExpenseWaivedRecoupable>N</isExpenseWaivedRecoupable>
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            <pricingServiceName>JPMorgan Chase Bank, National Association</pricingServiceName>
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            <pricingServiceName>London Stock Exchange Group PLC</pricingServiceName>
            <pricingServiceLei>213800QAUUUP6I445N30</pricingServiceLei>
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        <avgPortfolioSecuritiesValue>N/A</avgPortfolioSecuritiesValue>
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      <managementInvestmentQuestion>
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        <isBrokerageResearchPayment>N</isBrokerageResearchPayment>
        <dailyAvgNetAssets>9073715662.00361643</dailyAvgNetAssets>
        <hasLineOfCredit>N</hasLineOfCredit>
        <isInterfundLending>N</isInterfundLending>
        <isInterfundBorrowing>N</isInterfundBorrowing>
      </managementInvestmentQuestion>
      <managementInvestmentQuestion>
        <mgmtInvFundName>UBS Ultra Short Income Fund</mgmtInvFundName>
        <mgmtInvSeriesId>S000061955</mgmtInvSeriesId>
        <mgmtInvLei>549300S6VZYIBES1HD75</mgmtInvLei>
        <isFirstFilingByFund>N</isFirstFilingByFund>
        <numAuthorizedClass>3</numAuthorizedClass>
        <numAddedClass>0</numAddedClass>
        <numTerminatedClass>0</numTerminatedClass>
        <sharesOutstandings>
          <sharesOutstanding sharesOutstandingClassName="Class A" sharesOutstandingClassId="C000200717" sharesOutstandingTickerSymbol="USIAX"/>
          <sharesOutstanding sharesOutstandingClassName="Class I" sharesOutstandingClassId="C000200719" sharesOutstandingTickerSymbol="USDIX"/>
          <sharesOutstanding sharesOutstandingClassName="Class P" sharesOutstandingClassId="C000200718" sharesOutstandingTickerSymbol="USIPX"/>
        </sharesOutstandings>
        <fundType>N/A</fundType>
        <isNonDiversifiedCompany>N</isNonDiversifiedCompany>
        <isForeignSubsidiary>N</isForeignSubsidiary>
        <isFundSecuritiesLending>Y</isFundSecuritiesLending>
        <fundLendSecurities didFundLendSecurities="Y">
          <isFundLiquidated>N</isFundLiquidated>
          <isFundAdverselyImpacted>N</isFundAdverselyImpacted>
        </fundLendSecurities>
        <securityLendings>
          <securityLending>
            <securitiesAgentName>State Street Bank and Trust Company</securitiesAgentName>
            <securitiesAgentLei>571474TGEMMWANRLN572</securitiesAgentLei>
            <isSecuritiesAgentAffiliated>N</isSecuritiesAgentAffiliated>
            <securityAgentIdemnity isSecurityAgentIdemnity="Y">
              <idemnityProviders>
                <idemnityProvider idemnityProviderName="N/A" idemnityProviderLei="N/A"/>
              </idemnityProviders>
              <didIndemnificationRights>N</didIndemnificationRights>
            </securityAgentIdemnity>
          </securityLending>
        </securityLendings>
        <paymentToAgentManagers>
          <paymentToAgentManagerType>Cash collateral reinvestment fee</paymentToAgentManagerType>
          <paymentToAgentManagerType>Revenue sharing split</paymentToAgentManagerType>
        </paymentToAgentManagers>
        <avgPortfolioSecuritiesValue>1296648.22000000</avgPortfolioSecuritiesValue>
        <netIncomeSecuritiesLending>13313.00000000</netIncomeSecuritiesLending>
        <relyOnRuleTypes>
          <relyOnRuleType>Rule 10f-3 (17 CFR 270.10f-3)</relyOnRuleType>
          <relyOnRuleType>Rule 12d1-1 (17 CFR 270.12d1-1)</relyOnRuleType>
          <relyOnRuleType>Rule 32a-4 (17 CFR 270.32a-4)</relyOnRuleType>
        </relyOnRuleTypes>
        <isExpenseLimitationInPlace>Y</isExpenseLimitationInPlace>
        <isExpenseReducedOrWaived>Y</isExpenseReducedOrWaived>
        <isFeesWaivedRecoupable>N</isFeesWaivedRecoupable>
        <isExpenseWaivedRecoupable>N</isExpenseWaivedRecoupable>
        <investmentAdvisers>
          <investmentAdviser>
            <investmentAdviserName>UBS Asset Management (Americas) LLC</investmentAdviserName>
            <investmentAdviserFileNo>801-34910</investmentAdviserFileNo>
            <investmentAdviserCrdNo>000106838</investmentAdviserCrdNo>
            <investmentAdviserLei>F88SLSBEMHN5FUSNRO91</investmentAdviserLei>
            <investmentAdviserStateCountry investmentAdviserState="US-IL" investmentAdviserCountry="US"/>
            <isInvestmentAdviserHired>N</isInvestmentAdviserHired>
          </investmentAdviser>
        </investmentAdvisers>
        <transferAgents>
          <transferAgent>
            <transferAgentName>BNY Mellon Investment Servicing (US) Inc.</transferAgentName>
            <transferAgentFileNo>084-01761</transferAgentFileNo>
            <transferAgentLei>549300CFZQLI9QMJ1Z03</transferAgentLei>
            <transferAgentStateCountry transferAgentState="US-DE" transferAgentCountry="US"/>
            <isTransferAgentAffiliated>N</isTransferAgentAffiliated>
            <isTransferAgentSubAgent>N</isTransferAgentSubAgent>
          </transferAgent>
        </transferAgents>
        <isTransferAgentHiredOrTerminated>N</isTransferAgentHiredOrTerminated>
        <pricingServices>
          <pricingService>
            <pricingServiceName>S&amp;P Global Inc.</pricingServiceName>
            <pricingServiceLei>Y6X4K52KMJMZE7I7MY94</pricingServiceLei>
            <pricingServiceStateCountry pricingServiceState="US-NY" pricingServiceCountry="US"/>
            <isPricingServiceAffiliated>N</isPricingServiceAffiliated>
          </pricingService>
          <pricingService>
            <pricingServiceName>London Stock Exchange Group PLC</pricingServiceName>
            <pricingServiceLei>213800QAUUUP6I445N30</pricingServiceLei>
            <pricingServiceCountry>GB</pricingServiceCountry>
            <isPricingServiceAffiliated>N</isPricingServiceAffiliated>
          </pricingService>
          <pricingService>
            <pricingServiceName>JPMorgan Chase Bank, National Association</pricingServiceName>
            <pricingServiceLei>7H6GLXDRUGQFU57RNE97</pricingServiceLei>
            <pricingServiceStateCountry pricingServiceState="US-OH" pricingServiceCountry="US"/>
            <isPricingServiceAffiliated>N</isPricingServiceAffiliated>
          </pricingService>
        </pricingServices>
        <isPricingServiceHiredOrTerminated>Y</isPricingServiceHiredOrTerminated>
        <custodians>
          <custodian>
            <custodianName>Royal Bank of Canada</custodianName>
            <custodianLei>ES7IP3U3RHIGC71XBU11</custodianLei>
            <custodianCountry>CA</custodianCountry>
            <isCustodianAffiliated>N</isCustodianAffiliated>
            <isSubCustodian>Y</isSubCustodian>
            <custodyType>Foreign custodian - rule 17f-5 (17 CFR 270.17f-5)</custodyType>
          </custodian>
          <custodian>
            <custodianName>State Street Bank and Trust Company (Edinburgh, GB, Branch)</custodianName>
            <custodianLei>571474TGEMMWANRLN572</custodianLei>
            <custodianCountry>GB</custodianCountry>
            <isCustodianAffiliated>N</isCustodianAffiliated>
            <isSubCustodian>Y</isSubCustodian>
            <custodyType>Foreign custodian - rule 17f-5 (17 CFR 270.17f-5)</custodyType>
          </custodian>
          <custodian>
            <custodianName>BNP Paribas</custodianName>
            <custodianLei>R0MUWSFPU8MPRO8K5P83</custodianLei>
            <custodianCountry>FR</custodianCountry>
            <isCustodianAffiliated>N</isCustodianAffiliated>
            <isSubCustodian>Y</isSubCustodian>
            <custodyType>Foreign custodian - rule 17f-5 (17 CFR 270.17f-5)</custodyType>
          </custodian>
          <custodian>
            <custodianName>State Street Trust Company Canada</custodianName>
            <custodianLei>549300L71XG2CTQ2V827</custodianLei>
            <custodianCountry>CA</custodianCountry>
            <isCustodianAffiliated>N</isCustodianAffiliated>
            <isSubCustodian>Y</isSubCustodian>
            <custodyType>Foreign custodian - rule 17f-5 (17 CFR 270.17f-5)</custodyType>
          </custodian>
          <custodian>
            <custodianName>State Street Bank International GmbH</custodianName>
            <custodianLei>ZMHGNT7ZPKZ3UFZ8EO46</custodianLei>
            <custodianCountry>DE</custodianCountry>
            <isCustodianAffiliated>N</isCustodianAffiliated>
            <isSubCustodian>Y</isSubCustodian>
            <custodyType>Foreign custodian - rule 17f-5 (17 CFR 270.17f-5)</custodyType>
          </custodian>
          <custodian>
            <custodianName>Mizuho Bank, Ltd. (Minato ku, Tokyo, JP, Branch)</custodianName>
            <custodianLei>RB0PEZSDGCO3JS6CEU02</custodianLei>
            <custodianCountry>JP</custodianCountry>
            <isCustodianAffiliated>N</isCustodianAffiliated>
            <isSubCustodian>Y</isSubCustodian>
            <custodyType>Foreign custodian - rule 17f-5 (17 CFR 270.17f-5)</custodyType>
          </custodian>
          <custodian>
            <custodianName>Euroclear Bank</custodianName>
            <custodianLei>549300OZ46BRLZ8Y6F65</custodianLei>
            <custodianCountry>BE</custodianCountry>
            <isCustodianAffiliated>N</isCustodianAffiliated>
            <isSubCustodian>Y</isSubCustodian>
            <custodyType>Foreign securities depository - rule 17f-7 (17 CFR 270.17f-7)</custodyType>
          </custodian>
          <custodian>
            <custodianName>Intesa Sanpaolo S.p.A.</custodianName>
            <custodianLei>2W8N8UU78PMDQKZENC08</custodianLei>
            <custodianCountry>IT</custodianCountry>
            <isCustodianAffiliated>N</isCustodianAffiliated>
            <isSubCustodian>Y</isSubCustodian>
            <custodyType>Foreign custodian - rule 17f-5 (17 CFR 270.17f-5)</custodyType>
          </custodian>
          <custodian>
            <custodianName>State Street Bank and Trust Company</custodianName>
            <custodianLei>571474TGEMMWANRLN572</custodianLei>
            <custodianStateCountry custodianState="US-MA" custodianCountry="US"/>
            <isCustodianAffiliated>N</isCustodianAffiliated>
            <isSubCustodian>N</isSubCustodian>
            <custodyType>Bank - section 17(f)(1) (15 U.S.C. 80a-17(f)(1))</custodyType>
          </custodian>
        </custodians>
        <isCustodianHiredOrTerminated>N</isCustodianHiredOrTerminated>
        <shareholderServicingAgents>
          <shareholderServicingAgent>
            <shareholderServiceAgentName>BNY Mellon Investment Servicing (US) Inc.</shareholderServiceAgentName>
            <shareholderServiceAgentLei>549300CFZQLI9QMJ1Z03</shareholderServiceAgentLei>
            <shareholderServiceAgentStateCountry shareholderServiceAgentState="US-DE" shareholderServiceAgentCountry="US"/>
            <isShareholderServiceAgentAffiliated>N</isShareholderServiceAgentAffiliated>
            <isShareholderServiceAgentSubshare>N</isShareholderServiceAgentSubshare>
          </shareholderServicingAgent>
        </shareholderServicingAgents>
        <isShareholderServiceHiredTerminated>N</isShareholderServiceHiredTerminated>
        <admins>
          <admin>
            <adminName>UBS Asset Management (Americas) LLC</adminName>
            <adminLei>F88SLSBEMHN5FUSNRO91</adminLei>
            <adminStateCountry adminState="US-IL" adminCountry="US"/>
            <isAdminAffiliated>Y</isAdminAffiliated>
            <isAdminSubAdmin>N</isAdminSubAdmin>
          </admin>
        </admins>
        <isAdminHiredOrTerminated>N</isAdminHiredOrTerminated>
        <brokerDealers>
          <brokerDealer>
            <brokerDealerName>UBS Securities LLC</brokerDealerName>
            <brokerDealerFileNo>8-22651</brokerDealerFileNo>
            <brokerDealerCrdNo>000007654</brokerDealerCrdNo>
            <brokerDealerLei>T6FIZBDPKLYJKFCRVK44</brokerDealerLei>
            <brokerDealerStateCountry brokerDealerState="US-NY" brokerDealerCountry="US"/>
            <brokerDealerCommission>0.00000000</brokerDealerCommission>
          </brokerDealer>
        </brokerDealers>
        <aggregateCommission>0.00000000</aggregateCommission>
        <principalTransactions>
          <principalTransaction>
            <principalName>BNY Capital Markets, LLC</principalName>
            <principalFileNo>8-35255</principalFileNo>
            <principalCrdNo>000017454</principalCrdNo>
            <principalLei>VJW2DOOHGDT6PR0ZRO63</principalLei>
            <principalStateCountry principalState="US-NY" principalCountry="US"/>
            <principalTotalPurchaseSale>31889213.62000000</principalTotalPurchaseSale>
          </principalTransaction>
          <principalTransaction>
            <principalName>Wells Fargo Securities, LLC</principalName>
            <principalFileNo>8-65876</principalFileNo>
            <principalCrdNo>000126292</principalCrdNo>
            <principalLei>VYVVCKR63DVZZN70PB21</principalLei>
            <principalStateCountry principalState="US-NC" principalCountry="US"/>
            <principalTotalPurchaseSale>639422970.26000000</principalTotalPurchaseSale>
          </principalTransaction>
          <principalTransaction>
            <principalName>RBC Capital Markets, LLC</principalName>
            <principalFileNo>8-45411</principalFileNo>
            <principalCrdNo>000031194</principalCrdNo>
            <principalLei>549300LCO2FLSSVFFR64</principalLei>
            <principalStateCountry principalState="US-NY" principalCountry="US"/>
            <principalTotalPurchaseSale>93420868.45000000</principalTotalPurchaseSale>
          </principalTransaction>
          <principalTransaction>
            <principalName>State Street Bank and Trust Company</principalName>
            <principalFileNo>N/A</principalFileNo>
            <principalCrdNo>N/A</principalCrdNo>
            <principalLei>571474TGEMMWANRLN572</principalLei>
            <principalStateCountry principalState="US-MA" principalCountry="US"/>
            <principalTotalPurchaseSale>258343391.16000000</principalTotalPurchaseSale>
          </principalTransaction>
          <principalTransaction>
            <principalName>Citigroup Global Markets Inc.</principalName>
            <principalFileNo>8-8177</principalFileNo>
            <principalCrdNo>000007059</principalCrdNo>
            <principalLei>MBNUM2BPBDO7JBLYG310</principalLei>
            <principalStateCountry principalState="US-NY" principalCountry="US"/>
            <principalTotalPurchaseSale>16902363.88000000</principalTotalPurchaseSale>
          </principalTransaction>
          <principalTransaction>
            <principalName>Mizuho Securities USA LLC</principalName>
            <principalFileNo>8-37710</principalFileNo>
            <principalCrdNo>000019647</principalCrdNo>
            <principalLei>7TK5RJIZDFROZCA6XF66</principalLei>
            <principalStateCountry principalState="US-NY" principalCountry="US"/>
            <principalTotalPurchaseSale>73443723.79000000</principalTotalPurchaseSale>
          </principalTransaction>
          <principalTransaction>
            <principalName>J.P. Morgan Securities LLC</principalName>
            <principalFileNo>8-35008</principalFileNo>
            <principalCrdNo>000000079</principalCrdNo>
            <principalLei>ZBUT11V806EZRVTWT807</principalLei>
            <principalStateCountry principalState="US-NY" principalCountry="US"/>
            <principalTotalPurchaseSale>839903238.88000000</principalTotalPurchaseSale>
          </principalTransaction>
          <principalTransaction>
            <principalName>Goldman Sachs &amp; Co. LLC</principalName>
            <principalFileNo>8-129</principalFileNo>
            <principalCrdNo>000000361</principalCrdNo>
            <principalLei>FOR8UP27PHTHYVLBNG30</principalLei>
            <principalStateCountry principalState="US-NY" principalCountry="US"/>
            <principalTotalPurchaseSale>96941932.51000000</principalTotalPurchaseSale>
          </principalTransaction>
          <principalTransaction>
            <principalName>BofA Securities, Inc.</principalName>
            <principalFileNo>8-69787</principalFileNo>
            <principalCrdNo>000283942</principalCrdNo>
            <principalLei>549300HN4UKV1E2R3U73</principalLei>
            <principalStateCountry principalState="US-NY" principalCountry="US"/>
            <principalTotalPurchaseSale>3137240056.67000000</principalTotalPurchaseSale>
          </principalTransaction>
          <principalTransaction>
            <principalName>Barclays Capital Inc.</principalName>
            <principalFileNo>8-41342</principalFileNo>
            <principalCrdNo>000019714</principalCrdNo>
            <principalLei>AC28XWWI3WIBK2824319</principalLei>
            <principalStateCountry principalState="US-NY" principalCountry="US"/>
            <principalTotalPurchaseSale>108355901.67000000</principalTotalPurchaseSale>
          </principalTransaction>
        </principalTransactions>
        <principalAggregatePurchase>5420790355.36000000</principalAggregatePurchase>
        <isBrokerageResearchPayment>N</isBrokerageResearchPayment>
        <mnthlyAvgNetAssets>361877578.79307692</mnthlyAvgNetAssets>
        <hasLineOfCredit>N</hasLineOfCredit>
        <isInterfundLending>N</isInterfundLending>
        <isInterfundBorrowing>N</isInterfundBorrowing>
        <isSwingPricing>N</isSwingPricing>
      </managementInvestmentQuestion>
      <managementInvestmentQuestion>
        <mgmtInvFundName>UBS Select Treasury Institutional Fund</mgmtInvFundName>
        <mgmtInvSeriesId>S000002682</mgmtInvSeriesId>
        <mgmtInvLei>549300OA0OSRYE6ZYO90</mgmtInvLei>
        <isFirstFilingByFund>N</isFirstFilingByFund>
        <numAuthorizedClass>1</numAuthorizedClass>
        <numAddedClass>0</numAddedClass>
        <numTerminatedClass>0</numTerminatedClass>
        <sharesOutstandings>
          <sharesOutstanding sharesOutstandingClassName="UBS Select Treasury Institutional Fund" sharesOutstandingClassId="C000007334" sharesOutstandingTickerSymbol="SETXX"/>
        </sharesOutstandings>
        <fundTypes>
          <fundType>Money Market Fund</fundType>
          <masterFeederFundInfo fundType="Master-Feeder Fund">
            <masterFunds masterFundName="Treasury Master Fund" masterFundFileNo="811-22078" masterFundSECFileNo="801-34910" masterFundLei="549300XQ6V293JKF0677"/>
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        <isNonDiversifiedCompany>N</isNonDiversifiedCompany>
        <isForeignSubsidiary>N</isForeignSubsidiary>
        <isFundSecuritiesLending>N</isFundSecuritiesLending>
        <didFundLendSecurities>N</didFundLendSecurities>
        <paymentToAgentManagerType>N/A</paymentToAgentManagerType>
        <avgPortfolioSecuritiesValue>N/A</avgPortfolioSecuritiesValue>
        <netIncomeSecuritiesLending>N/A</netIncomeSecuritiesLending>
        <relyOnRuleTypes>
          <relyOnRuleType>Rule 32a-4 (17 CFR 270.32a-4)</relyOnRuleType>
          <relyOnRuleType>Rule 17a-8 (17 CFR 270.17a-8)</relyOnRuleType>
        </relyOnRuleTypes>
        <isExpenseLimitationInPlace>Y</isExpenseLimitationInPlace>
        <isExpenseReducedOrWaived>N</isExpenseReducedOrWaived>
        <isFeesWaivedRecoupable>N</isFeesWaivedRecoupable>
        <isExpenseWaivedRecoupable>N</isExpenseWaivedRecoupable>
        <investmentAdvisers>
          <investmentAdviser>
            <investmentAdviserName>UBS Asset Management (Americas) LLC</investmentAdviserName>
            <investmentAdviserFileNo>801-34910</investmentAdviserFileNo>
            <investmentAdviserCrdNo>000106838</investmentAdviserCrdNo>
            <investmentAdviserLei>F88SLSBEMHN5FUSNRO91</investmentAdviserLei>
            <investmentAdviserStateCountry investmentAdviserState="US-IL" investmentAdviserCountry="US"/>
            <isInvestmentAdviserHired>N</isInvestmentAdviserHired>
          </investmentAdviser>
        </investmentAdvisers>
        <transferAgents>
          <transferAgent>
            <transferAgentName>BNY Mellon Investment Servicing (US) Inc.</transferAgentName>
            <transferAgentFileNo>084-01761</transferAgentFileNo>
            <transferAgentLei>549300CFZQLI9QMJ1Z03</transferAgentLei>
            <transferAgentStateCountry transferAgentState="US-DE" transferAgentCountry="US"/>
            <isTransferAgentAffiliated>N</isTransferAgentAffiliated>
            <isTransferAgentSubAgent>N</isTransferAgentSubAgent>
          </transferAgent>
        </transferAgents>
        <isTransferAgentHiredOrTerminated>N</isTransferAgentHiredOrTerminated>
        <pricingServices>
          <pricingService>
            <pricingServiceName>JPMorgan Chase Bank, National Association</pricingServiceName>
            <pricingServiceLei>7H6GLXDRUGQFU57RNE97</pricingServiceLei>
            <pricingServiceStateCountry pricingServiceState="US-OH" pricingServiceCountry="US"/>
            <isPricingServiceAffiliated>N</isPricingServiceAffiliated>
          </pricingService>
          <pricingService>
            <pricingServiceName>London Stock Exchange Group PLC</pricingServiceName>
            <pricingServiceLei>213800QAUUUP6I445N30</pricingServiceLei>
            <pricingServiceCountry>GB</pricingServiceCountry>
            <isPricingServiceAffiliated>N</isPricingServiceAffiliated>
          </pricingService>
          <pricingService>
            <pricingServiceName>S&amp;P Global Inc.</pricingServiceName>
            <pricingServiceLei>Y6X4K52KMJMZE7I7MY94</pricingServiceLei>
            <pricingServiceStateCountry pricingServiceState="US-NY" pricingServiceCountry="US"/>
            <isPricingServiceAffiliated>N</isPricingServiceAffiliated>
          </pricingService>
        </pricingServices>
        <isPricingServiceHiredOrTerminated>Y</isPricingServiceHiredOrTerminated>
        <custodians>
          <custodian>
            <custodianName>State Street Bank and Trust Company</custodianName>
            <custodianLei>571474TGEMMWANRLN572</custodianLei>
            <custodianStateCountry custodianState="US-MA" custodianCountry="US"/>
            <isCustodianAffiliated>N</isCustodianAffiliated>
            <isSubCustodian>N</isSubCustodian>
            <custodyType>Bank - section 17(f)(1) (15 U.S.C. 80a-17(f)(1))</custodyType>
          </custodian>
        </custodians>
        <isCustodianHiredOrTerminated>N</isCustodianHiredOrTerminated>
        <shareholderServicingAgents>
          <shareholderServicingAgent>
            <shareholderServiceAgentName>BNY Mellon Investment Servicing (US) Inc.</shareholderServiceAgentName>
            <shareholderServiceAgentLei>549300CFZQLI9QMJ1Z03</shareholderServiceAgentLei>
            <shareholderServiceAgentStateCountry shareholderServiceAgentState="US-DE" shareholderServiceAgentCountry="US"/>
            <isShareholderServiceAgentAffiliated>N</isShareholderServiceAgentAffiliated>
            <isShareholderServiceAgentSubshare>N</isShareholderServiceAgentSubshare>
          </shareholderServicingAgent>
        </shareholderServicingAgents>
        <isShareholderServiceHiredTerminated>N</isShareholderServiceHiredTerminated>
        <admins>
          <admin>
            <adminName>UBS Asset Management (Americas) LLC</adminName>
            <adminLei>F88SLSBEMHN5FUSNRO91</adminLei>
            <adminStateCountry adminState="US-IL" adminCountry="US"/>
            <isAdminAffiliated>Y</isAdminAffiliated>
            <isAdminSubAdmin>N</isAdminSubAdmin>
          </admin>
        </admins>
        <isAdminHiredOrTerminated>N</isAdminHiredOrTerminated>
        <brokerDealers>
          <brokerDealer>
            <brokerDealerName>UBS Securities LLC</brokerDealerName>
            <brokerDealerFileNo>8-22651</brokerDealerFileNo>
            <brokerDealerCrdNo>000007654</brokerDealerCrdNo>
            <brokerDealerLei>T6FIZBDPKLYJKFCRVK44</brokerDealerLei>
            <brokerDealerStateCountry brokerDealerState="US-NY" brokerDealerCountry="US"/>
            <brokerDealerCommission>0.00000000</brokerDealerCommission>
          </brokerDealer>
        </brokerDealers>
        <aggregateCommission>0.00000000</aggregateCommission>
        <principalAggregatePurchase>0.00000000</principalAggregatePurchase>
        <isBrokerageResearchPayment>N</isBrokerageResearchPayment>
        <dailyAvgNetAssets>18411421181.44312328</dailyAvgNetAssets>
        <hasLineOfCredit>N</hasLineOfCredit>
        <isInterfundLending>N</isInterfundLending>
        <isInterfundBorrowing>N</isInterfundBorrowing>
      </managementInvestmentQuestion>
    </managementInvestmentQuestionSeriesInfo>
    <attachmentsTab>
      <isIPAReportInternalControl>true</isIPAReportInternalControl>
    </attachmentsTab>
    <signature registrantSignedName="UBS SERIES FUNDS" signedDate="2025-07-11" signature="Joanne Kilkeary" title="Vice President, Treasurer and Principal Accounting Officer"/>
  </formData>
</edgarSubmission>
