Strategy. Principal investments Under normal circumstances, the fund invests at least 80% of its net assets (plus the amount of any borrowing for investment purposes) in fixed income securities, which may be represented by derivatives or investments in securities of other investment companies that invest primarily in fixed income securities. Such investments may include US government and foreign government bonds (including bonds issued by supranational and quasi-governmental entities and mortgage-backed securities), municipal fixed income investments (including tax-exempt municipal securities), corporate bonds (including mortgage- and asset-backed securities of private issuers, Eurodollar certificates of deposit, Eurodollar bonds and Yankee bonds) and bank loans. There are different types of US government securities, including those issued or guaranteed by the US government, its agencies and … Show more… Principal investments Under normal circumstances, the fund invests at least 80% of its net assets (plus the amount of any borrowing for investment purposes) in fixed income securities, which may be represented by derivatives or investments in securities of other investment companies that invest primarily in fixed income securities. Such investments may include US government and foreign government bonds (including bonds issued by supranational and quasi-governmental entities and mortgage-backed securities), municipal fixed income investments (including tax-exempt municipal securities), corporate bonds (including mortgage- and asset-backed securities of private issuers, Eurodollar certificates of deposit, Eurodollar bonds and Yankee bonds) and bank loans. 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. The fund may invest in bonds that are investment grade at the time of purchase. The fund may also invest, in the aggregate, up to 20% of its total assets (measured at the time of purchase) in (1) bonds that are below investment grade at the time of purchase (or unrated bonds of equivalent quality) (commonly known as "junk bonds"), (2) non-US dollar denominated securities, and (3) fixed income securities of issuers located in emerging markets. The fund may also invest in equity securities, such as preferred shares and securities convertible into stocks. The fund invests in bonds of varying maturities. It normally limits its overall portfolio duration to within +/- 50% of the duration of the Bloomberg US Aggregate Bond Index, which as of July 31, 2025 was approximately 6.03 years and may change over time. Duration is a measure of the fund's exposure to interest rate riska longer duration means that changes in market interest rates are likely to have a larger effect on the value of the fund's portfolio. The fund may invest in "to be announced" or "TBA" securities, which are mortgage-backed securities that usually are traded on a forward commitment basis with an approximate principal amount and no defined maturity date, issued or guaranteed by US government agencies and instrumentalities. The fund also may engage in TBA and Treasury "roll" transactions. A TBA roll transaction is a strategy whereby the fund decides to sell one TBA security and buy another TBA security due at a later date (Treasury roll transactions differ in that the underlying securities are US Treasury securities). The fund may, but is not required to, use exchange-traded or over-the-counter derivative instruments for risk management purposes or to attempt to increase total returns. The derivatives in which the fund invests include swap agreements (specifically, interest rate swaps) and currency forward agreements. These derivatives may be used for risk management purposes, such as managing the risk profile of the fund. In addition, the derivative instruments listed above may be used to enhance returns or in place of direct investments. Futures, swaps and swaptions also may be used to adjust the fund's portfolio duration. The fund engages in frequent trading from time to time and consequently, the fund's investment strategies can result in high portfolio turnover. Management process The fund employs a "manager of managers" structure. UBS AM, the fund's manager and primary provider of investment advisory services, has the ultimate authority, subject to oversight by the fund's board, to oversee the fund's subadvisor(s) and recommend their hiring, termination and replacement, and to allocate assets among the fund's subadvisor(s). The relative value of each subadvisor's share of the fund's assets may change over time. UBS AM's investment process begins with subadvisor selection. UBS AM's portfolio management team constructs a list of potential subadvisors based on information primarily from internal sources and the team's collective knowledge of the industry, but also supplemented by external sources. The team then focuses its research on that list to identify a small number of the most attractive candidates. This research includes analyzing the portfolio holdings and/or positioning of a subadvisor's investment strategy to understand whether the allocation of risk and the drivers of alpha are consistent with the subadvisor's investment philosophy and stated strengths. The most attractive sub-set of those subadvisors is then selected for in-depth, on-site due diligence meetings with representatives from the investment, operations and compliance groups within UBS AM. The due diligence information is then synthesized to select the most attractive candidate(s) for the fund, subject to the board's approval. In managing the fund and overseeing the fund's subadvisor(s), UBS AM views its research process as an ongoing one, as the team continually seeks to confirm a subadvisor's investment thesis over the appropriate investment horizon. In general, UBS AM leverages its research and market knowledge to construct funds with exposure to various subadvisors that are expected, in combination, to produce the desired overall fund characteristics. UBS AM's ongoing monitoring and risk management process incorporates daily, weekly, monthly, quarterly and annual responsibilities designed to monitor the drivers of fund risk and performance at the subadvisor level and at the overall fund level. Through this process, UBS AM may adjust a fund's positioning by altering its allocation weights across subadvisors within the fund and/or by changing the specific subadvisors within the fund. The subadvisor utilizes a strategy that seeks to invest in a diversified portfolio of fixed income instruments that are performing, durable, and available at an attractive valuation, including floating or variable rate debt instruments. Show less