"And you're guaranteeing yourself a loss with the SPDR ETF," Boccellari added, even though the ETF invests in no-risk government Treasury bills with short maturities. The five-year return is negative .05 percent, through Jan. 23, according to Morningstar data.
Investors also need to understand that trading costs can add up, too, said Boccellari. Buying these ETFs through brokers may mean that you're paying $30 or $50 to buy or sell. "Those costs also eat up yields," he added, "so investors need to be aware of that."
Opt for longer-term bonds instead, say some experts. Lessard likes the iShares 1-3 year Credit Bond (CSJ), which yields .94 percent and is up .39 percent so far this year through Jan. 23, according to Morningstar, and 1.93 percent over five years on an annualized basis. He also likes the Vanguard Intermediate term bond ETF (BIV), which has had even stronger returns. The ETF yields 2.83 percent and is up 2.26 percent this year, through Jan. 23, according to Morningstar data, and 6 percent over five years, through Jan. 23, on an annualized basis.