New York (CNN Business) US investors think way too highly of America. Millennials have more cash than they need and not enough stocks. And nobody actually thinks owning bitcoin is a good idea.

Those are some of the findings from a recent online survey of 1,000 investors conducted by asset management firm Legg Mason between late July and late August.

Michael LaBella, head of global equity strategy at QS Investors, a Legg Mason affiliate, said he was surprised that investors remained so optimistic about the US stock market considering that the bull market will hit its 10th anniversary in March. This is one of the longest US bull markets ever, but the rest of the world hasn't performed as well over the past decade.

Still, two-thirds of the respondents indicated that they expected the US stock market to keep rising over the next twelve months, according to the survey. Seventy-three percent of those surveyed said they thought the United States was the best investing opportunity -- despite worries about the trade war with China and rising interest rates.

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"Investors are broadly more bullish but they have more exposure to the US than international markets," LaBella said. "There is an opportunity in international markets and people are under allocated there."

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