The willingness of mutual fund shareholders to take substantial or above-average risk remained at 30% of all mutual fund-owning households in May 2010, the same as in May 2009, the Investment Company Institute said.

Back in May 2008, 37% of mutual fund-owning households were willing to take on additional risk. The ICI attributed the decline to lackluster equity markets and Baby Boomers approaching retirement.

“In recent years, relatively strong bond fund flows and weaker than expected equity fund flows in part reflected investors’ reduced tolerance for risk and the aging of the U.S. population,” said ICI Chief Economist Brian Reid. “Stock and bond market returns also contribute to the mutual fund flow patterns observed.”

Indeed, fund performance continues to dominate investors’ opinions of the mutual fund industry, with two-thirds of investors saying this is a “very” important factor, the ICI survey also found. They were next influenced by the opinions of their financial adviser on fund companies, their own personal interaction with fund companies and current events in the financial markets.

As the stock market moved upward in the earlier part of 2010, so did the favorability rating of mutual funds; the rating rose to 67% this year, up from 64% the year before.