Money funds, once considered a safe place to park cash, could become moderately risky again when the government program hastily initiated last year to guarantee money fund deposits expires on Sept. 18.

In 2008 the colossal Reserve Primary Fund, with $62.5 billion in its portfolio "broke the buck" when Lehman Brothers defaulted on $785 million in bonds which the fund held. Investor redemptions skyrocketed.

This prompted then Treasury secretary Henry Paulson's unprecedented intervention to protect all money market assets, approximately $3.5 trillion, and thus avert a panic, writes Joe Nocera in The New York Times.

"Here we are a year later and the money market fund business seems back to normal," Nocera writes.

"No other money funds have broken the buck."

But now the safety net is gone.

Accordingly, the SEC is proposing new rules for money funds, including stricter liquidity standards.

Some banks, in an effort to attract depositor dollars, are offering more than 2 percent on money market deposits — better than an average non-bank money market yield of less than one percent — with the usual FDIC guarantee up to $250,000, according to Kiplinger's Personal Finance Magazine.