Strategy. Main investments. Under normal market conditions, the fund invests at least 65% of its total assets in fixed income securities rated, at the time of purchase, within the top four credit rating categories by a nationally recognized statistical rating organization (a NRSRO) (or, if unrated, determined by the fund's investment advisor to be of similar quality). The fund may invest in securities of varying maturities. The fund normally seeks to maintain an average portfolio duration (a measure of sensitivity to interest rate movements) of no longer than three years by investing in fixed income securities with short-to intermediate-term maturities. The fund may also invest up to 10% of its assets in below investment-grade fixed income securities (junk bonds) of domestic … Show more… Main investments. Under normal market conditions, the fund invests at least 65% of its total assets in fixed income securities rated, at the time of purchase, within the top four credit rating categories by a nationally recognized statistical rating organization (a NRSRO) (or, if unrated, determined by the fund's investment advisor to be of similar quality). The fund may invest in securities of varying maturities. The fund normally seeks to maintain an average portfolio duration (a measure of sensitivity to interest rate movements) of no longer than three years by investing in fixed income securities with short-to intermediate-term maturities. The fund may also invest up to 10% of its assets in below investment-grade fixed income securities (junk bonds) of domestic and foreign issuers which are rated in the fifth and sixth highest credit rating categories by the three major NRSROs (Moodys Investor Services, Inc., Fitch Investors Services, Inc., and Standard and Poors Ratings Group) or, if unrated, determined by the fund's investment advisor to be of similar quality, including those whose issuers are located in countries with new or emerging securities markets. Compared to investment-grade debt securities, junk bonds generally pay higher yields, have higher volatility and higher risk of default on payments of interest or principal. Fixed income securities in which the fund may invest include US government securities or obligations that are issued or guaranteed by the US Treasury or by agencies or instrumentalities of the US government; obligations backed by such US government securities; US dollar-denominated fixed income securities of domestic or foreign corporations, including adjustable rate loans that have a senior right to payment (senior loans) and other floating rate debt instruments; US dollar-denominated fixed income securities of foreign governments or supranational entities; US dollar-denominated asset-backed securities issued by domestic or foreign entities; non-US dollar-denominated fixed income securities of foreign corporations, foreign governments or supranational entities; mortgage pass-through securities issued by governmental and non-governmental issuers; collateralized mortgage obligations, real estate mortgage investment conduits and commercial mortgage-backed securities; collateralized loan obligations; short-term investments, including money market mutual funds. Portfolio management seeks diversified exposure to higher yielding mortgage, corporate and asset-backed sectors of the investment-grade fixed income markets. Senior loans may have longer trade settlement periods than other types of investments. The fund invests in short-term investments to meet shareholder withdrawals and other liquidity needs. Short-term investments will be rated at the time of purchase within one of the top two short-term rating categories by a NRSRO or, if unrated, determined by the funds investment advisor to be of similar quality. The fund may also invest in Rule 144A securities, securities or instruments on a when-issued, delayed delivery or forward commitment basis (e.g., TBA securities), repurchase agreements, reverse repurchase agreements and dollar rolls. Transactions involving securities or instruments on a when-issued, delayed delivery or forward commitment basis (e.g., TBA securities) that have settlement dates greater than 35 days and transactions in reverse repurchase agreements are treated as derivatives by the fund and are subject to the fund's policies and procedures with respect to derivatives. Transactions with settlement dates greater than 35 days generally are used for non-hedging purposes to seek to enhance potential gains. Management process. Portfolio management uses a top-down and bottom-up approach, first focusing on sector allocations, then using relative value analysis to select the best securities within each sector. When selecting securities, portfolio management analyzes such factors as credit quality, interest rate sensitivity and spread relationships between individual bonds. Portfolio management generally considers environmental, social and governance (ESG) factors that it believes to be financially material. Derivatives. Portfolio management generally may use futures contracts, which are a type of derivative (financial instruments whose performance is derived, at least in part, from the performance of an underlying asset, security or index), for duration management (i.e., reducing or increasing the sensitivity of the fund's portfolio to interest rate changes) or for non-hedging purposes to seek to enhance potential gains. In addition, portfolio management generally may use forward currency contracts to hedge the fund's exposure to changes in foreign currency exchange rates on its foreign currency denominated portfolio holdings, to facilitate transactions in foreign currency denominated securities or for non-hedging purposes to seek to enhance potential gains. Portfolio management generally may also use credit default swaps to seek to increase the funds income, to gain exposure to a bond issuers credit quality characteristics without directly investing in the bond, or to hedge the risk of default on bonds held in the funds portfolio. The fund may also use other types of derivatives (i) for hedging purposes; (ii) for risk management; (iii) for non-hedging purposes to seek to enhance potential gains; or (iv) as a substitute for direct investment in a particular asset class or to keep cash on hand to meet shareholder redemptions. Securities lending. The fund may lend securities (up to one-third of total assets) to approved institutions, such as registered broker-dealers, pooled investment vehicles, banks and other financial institutions. In connection with such loans, the fund receives liquid collateral in an amount that is based on the type and value of the securities being lent, with riskier securities generally requiring higher levels of collateral. Active trading. The fund may trade securities actively and this may lead to high portfolio turnover. Show less