Most IRA investors did not abandon stocks during the market decline of 2008 and 2009, but they have been wary of adding more holdings during the market rebound, according to a new survey.

The study by Vanguard, entitled "Equity Abandonment in 2008-2009: Lower Among Balanced Fund Investors," found that only about 1% of investors completely sold out of the stock market during the collapse that began in the fall of 2008.

The report analyzed the activity of 2.7 million IRA investors from 2007 to October 2009.

Balanced investors tended to stick with their funds, especially those who held only one balanced fund, which includes both stocks and bonds. The abandonment rate of these balanced investors was about 50% lower than that of investors who owned equity funds, but no balanced funds.

"One explanation for this behavior is that individual investors who see only the performance of the overall balanced fund and not the most volatile holdings within the fund may be less likely to react to short-term market performance," said John Ameriks, head of Vanguard Investment Counseling and Research and a co-author of the study.

The survey, however, found investors were skittish about stocks even during the market rebound in 2009.

Through November 2009, investors pulled $500 billion from money market funds, and, despite one of the strongest bull markets in history, withdrew $9 billion from stock funds. During the same period, bond funds attracted $340 billion-presumably from investors unnerved by the quickest severe market decline in U.S. history, according to the survey.