Wealthy investors credit big stock market gains for the bulk of the increases in their net worth, according to a survey released last week.

Eighty-eight percent of 150 affluent investors polled by U.S. Trust Corp., New York, said the bull run in the stock market benefited them, while only 12% said it had little or no impact.

Ownership of stocks boosted the net worth of the survey respondents by an average of 43% since 1993, as their stock investments increased in value on average by 69%.

The gains could be causing an overweighting of portfolios toward equities, noted Jeffrey S. Maurer, president and chief operating officer of U.S. Trust.

Suggesting that a portfolio of someone who has plenty of time to plan for retirement should have 50% to 70% of investments in equities, he added that U.S. Trust is "leading the way" for its clients and recommending alternatives if they are not diversified.

"Our clients have grown almost complacent to a certain extent with their asset allocation," Mr. Maurer said.

It is sometimes hard to persuade investors to pull back, even a tad, from a well-performing asset class, especially the U.S. stock market, he added.

Sixty-six percent of the survey respondents said it was unlikely they would sell stocks that have appreciated, but 30% said they might.

Those investors who have realized gains transferred the money to cash, or invested the proceeds in bonds, foreign stocks, and real estate.

Allocating a portion of equity investments to international stocks is a good hedge, Mr. Maurer said.

Outside of allocations to equities or fixed income, U.S. Trust recommends investing in alternative vehicles, such as venture capital or leveraged buyout funds, because their performances do not correlate to traditional stock or debt markets.

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