A group of five large mutual fund families—including T. Rowe Price and Wellington Management—broadly increased their investments in venture capital-backed tech companies last year, according to CB Insights. Businesses getting capital from mutual funds include ride-sharing service Uber and room rental platform Airbnb.
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Prominent investors have recently warned about the risks posed by the funding flowing into tech start-ups. For instance, Uber was recently valued at $40 billion, while photo-sharing app Snapchat and others have jumped past the $10 billion valuation mark.
But mutual fund exposure has not reached a level that should trouble the average investor, Ritter said.
"I'm not especially worried about it," he said.
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Private ventures account for less than 1 percent of equity mutual fund assets, Ritter said. Additionally, the funds cannot invest more than 15 percent of their assets in illiquid securities like start-ups.