(Bloomberg News) Millionaires added U.S. stocks more than any other asset in the latest year as average investors fled to bonds, according to a survey by Fidelity Investments.

Twenty percent of the 1,020 households surveyed said they bought individual domestic equities in the 12 months ended in March, the Boston-based mutual fund firm said. Cash ranked second, with 13 percent saying they added to that asset class. Eleven percent purchased exchange-traded funds, and 10 percent each added individual U.S. bonds or domestic stock funds.

The broader investing public has sought refuge in fixed income since the global credit crisis sent the Standard & Poor's 500 Index down 38 percent in 2008, eight years after the meltdown in technology stocks. U.S. equity mutual funds suffered net withdrawals of $130 billion in the 12 months ended March 31, according to Chicago-based research firm Morningstar Inc. Bond funds attracted $191 billion. The S&P 500 gained 9.2 percent this year through yesterday.

"They're probably ahead of the average investor in how they view opportunities," Bob Oros, executive vice president in Fidelity's institutional wealth services group, said of millionaires in an interview. "They're becoming less and less risk-averse."

The firm, which had $3.5 trillion in assets under administration as of May 31, didn't ask how much the millionaires invested. There are 5.13 million U.S. households with at least $1 million in investable assets, or 4.3 percent of the population, according to a May report by the Boston Consulting Group.

Positive Outlook

Millionaires' outlook for the future of the economy was the most positive it's been since the annual study started in 2006, Oros said. Twelve percent said they would be willing to put aside a large portion of their portfolio for risky investments, compared with 8.2 percent three years ago in the wake of the financial crisis.

The households surveyed had at least $1 million in investable assets, excluding retirement savings and real estate, and respondents weren't necessarily Fidelity clients. The average respondent was age 61 and had $3.05 million in investable assets.

About 26 percent said they don't feel wealthy and would need a median of $5 million to feel rich. That compares with 42 percent of millionaires in 2011 who said they'd need $7.5 million.

"There's been some recalibration with this group in terms of what they need," Oros said.

About 86 percent of the millionaires surveyed said they were self-made, rather than born wealthy. That's why the group may be more comfortable with investing in U.S. stocks as many have seen capital appreciation in their own experience, he said.

'Proxy' Group

"The average investor would be wise to look at this group as a proxy," Oros said. "They are leading the way back in."

The Tiger 21 investment network also is seeing wealthy investors shift their portfolios toward riskier assets, albeit to private equity, said Michael Sonnenfeldt, founder of the New York-based group.

Its 192 members, most of whom have a net worth of at least $10 million, on average had 18 percent of their investments in private equity in the second quarter, a four percentage point increase from the prior three months, according to a July 17 report.

Their allocation to equities remained at 22 percent and their portion in fixed income, 13 percent, was the lowest since the tracking began in 2007, the study showed.

"It's so difficult to generate positive returns on traditional investments," Sonnenfeldt said in a phone interview yesterday. "They've realized they have to take a little more risk than maybe even is in their perfect comfort zone."

'Nervous' Tigers

Members still have a significant portion of their assets in cash, or 13 percent as of June 30, because they are "very nervous" as Europe struggles with the sovereign-debt crisis and the U.S. economy remains sluggish, he said.

About 7 percent of millionaires surveyed by Fidelity said they added alternative investments such as private equity and structured products to their holdings.

Fidelity, the second-largest U.S. mutual fund company, partnered with Bellomy Research Inc., based in Winston-Salem, North Carolina, to conduct the study via the Internet.