Money market rates are sitting at all-time lows, and if the economy doesn't perk up, they could be stuck at these levels for most of the year. And though basement-level rates are a plus for borrowers, they're a minus for corporations that have funds to invest for short periods of time. With the average seven-day taxable yield at 0.84% in mid-January and no relief in sight, what's a treasurer to do?

"I think everybody's trying to reach for yield," says Mark Preston, a portfolio manager at $10.6 billion Humana Inc. in Louisville, Ky. But he warns that, "What you want to look at is if you're compensated for the risk you're taking. If you're not being compensated, obviously you want to shy away from that."

David Gobberdiel, a vice president in the investment department of Wells Fargo Financial, a subsidiary of Wells Fargo & Co., admits to some wariness after last year's "blow up in commercial paper." He decided a few months ago to move some of his company's short-term money into a fund, run by Reserve Funds, that contains only Treasuries, agencies and bank CDs–and no commercial paper. He adds, though, that yield is "of secondary importance" to him because his company's money tends to be in the market so briefly.