The European debt crisis would pose a threat to U.S. money-market mutual funds if a rash of sovereign defaults caused big banks to fail to meet obligations within the next three months.

 "It would take a very rapid decline and not just in the smaller European countries" for the debt crisis to threaten U.S. money funds, George "Gus" Sauter, chief investment officer at Vanguard Group Inc. in Valley Forge, Pennsylvania, said in an interview. "You'd probably have to see Spain and Italy get into difficult shape."

Greek lawmakers are scheduled to vote this week on a five-year austerity plan for the cash-strapped nation to secure more international aid and avoid the euro area's first sovereign default. Money funds could be hurt by a default because they have lent to European banks that, in turn, have lent to Greece and other heavily indebted European countries.