The so-called fiscal cliff agreement that averted steep tax increases apparently helped boost investor confidence: The flow of cash into stock mutual funds during the first week of 2013 was the largest in more than 11 years.

Mutual funds investing in US stocks attracted $4 billion in net deposits during the weeklong period that ended Wednesday, and funds investing primarily in foreign stocks took in about $3.5 billion, according to preliminary data from Lipper, a unit of Thomson Reuters.