The latter group includes managers of mutual funds "who want to raise liquidity to meet anticipated redemptions," he said.

To meet redemptions, the Fidelity fund can keep up to 20 percent of its assets in money markets or other short-term paper.

First, such funds were forced to sell to meet redemptions, the study reported, thus realizing capital gains that resulted in bigger tax liabilities for investors.

The funds could therefore avoid the need to sell stocks to meet redemptions, thus helping to minimize taxable gains.

To meet redemptions, they may have to go into the markets the next day and sell shares, potentially at much lower prices.

Frequent trades inflate fees, force managers to sell stocks to meet redemptions and can add to tax bills.

Because exchange funds are traded in-kind by market specialists, shares need not be sold to meet redemptions.

The typical fund must hold a significant amount of cash so that it can meet redemptions.

Some also may have come from fund managers who were trying to raise cash to meet redemptions, real or anticipated.

He says the infusion of money this year makes his work less stressful - "no need to worry about having cash to meet redemptions."