After several weeks of caution, mutual fund investors appear to be coming back into the market, as investors plunked down an estimated $6.1 billion for the two business days ending Dec. 28, according to

TrimTabs.com

. U.S. funds saw inflows of more than $5 billion for the two days ending Thursday. International funds had inflows of almost $1.1 billion. The latest inflows come on the heels of the almost $10 billion that investors put into the market for the two business days ending Dec. 26.

During the two market days ending Dec. 28, the

Nasdaq

lifted 2.6%, the

Dow

increased 1.7% and the

S&P 500

gained 1.5%.