Money-market managers take a hit so you don't have to. By Joan Goldwasser, Senior Reporter February 28, 2009 The borrower's boon is the saver's bust: With yields on short-term Treasury bills stuck near 0%, money-market funds that hold these securities are struggling to keep their returns positive, after fees. Some funds are investing in longer-term securities, which extends the average maturity of the fund and garners a little extra yield without compromising safety.And don't be concerned if your fund has closed to new investors or limited deposits, as Vanguard, Schwab and Fidelity have. It's easier to maintain yield without dealing with heavy cash flows in and out of the fund. To earn the best returns, follow these rules: Shop around. Vanguard's Treasury fund currently yields 0.84%, more than four times the average. Manager David Glocke anticipated the rate decline and locked in higher yields. Move your cash. U.S. Treasury funds yield just 0.18% on average. Other money-market funds can invest more broadly and are still safe. U.S. government funds, yielding 0.47% on average, can purchase federal agency debt. Prime funds, yielding 0.89%, can buy higher-yielding commercial paper, floating-rate notes and bank deposits. Advertisement Look for a fee waiver. Some 60% of money-market funds already waive a portion of their fees; others may follow. Insist on rock-bottom expenses. The two top-yielding funds, Vanguard Prime, currently yielding 2.35%, and Fidelity Select, 2.05%, both sport lower-than-average expense ratios: 0.28% and 0.36% of assets, respectively.