Corporate treasuries are increasingly investing their mountains of cash in prime money market funds, in a sign that the extreme caution that characterized companies' short-term investing in the wake of the financial crisis is giving way to a renewed search for higher yields.

In a recent survey of finance executives at more than 60 U.S. companies conducted by Treasury Curve, a platform for institutional money market investing, 69% say that in 2010, they put cash into prime funds, which invest in short-term corporate securities. Even if prime funds are rated Triple-A, they're viewed as riskier than government-backed securities. In 2009, the first year of Treasury Curve's survey, just 49% invested in prime funds.

Meanwhile, 77% say they invested in 2010 in governments, such as agency securities or funds holding agency securities, little changed from 79% in 2009, while 77% invested in Treasury paper or funds, vs. 78% in 2009. More than 60% of respondents represented corporate treasuries, and the rest state or local governments and financial institutions.