Investors stepped up their sales of mutual funds this week, pulling out even more of their money than a week ago. Equity funds saw $12.25 billion walk out the door the week ended Wednesday, net of new purchases. That was up from $10.31 billion the previous week, according to TrimTabs Investment Research of Santa Rosa, Calif. Investors pulled a net $8.9 billion from funds that invest primarily in U.S. stocks, down from $9.58 billion the previous week. They pulled a net $3.35 billion out of funds that invest primarily in non-U.S. stocks, up from $728 million the previous week. Conrad Gann, chief operating officer at TrimTabs, said concerns about the economy appear to be a factor behind the increased outflows. "People are probably a little more nervous," he said, "and we haven't rounded the corner yet in terms of more optimistic conditions." Bond funds took inflows $1.59 billion, down from $2.52 billion during the previous week. Hybrid funds, which invest in both stocks and bonds, took in $680 million, down from $1.08 billion the previous week. The Dow Jones Industrial Average closed at 12,735.31 Wednesday, down 2.4% on from 13,043.96 a week earlier. Investors also pulled money out of exchange-traded funds that invest in U.S. stocks, which had outflows of $7.79 billion during the week. But that was down from $9.87 billion the previous week. ETFs that invest in non-U.S. stocks saw a net $1.09 billion walk out the door, reversing the of $1.31 billion they took in the previous week.