Mom and pop are running for the hills.

Since July, American households -- which account for almost all mutual fund investors -- have pulled money both from mutual funds that invest in stocks and those that invest in bonds. It’s the first time since 2008 that both asset classes have recorded back-to-back monthly withdrawals, according to a report by Credit Suisse.

Credit Suisse estimates $6.5 billion left equity funds in July as $8.4 billion was pulled from bond funds, citing weekly data from the Investment Company Institute as of Aug. 19. Those outflows were followed up in the first three weeks of August, when investors withdrew $1.6 billion from stocks and $8.1 billion from bonds, said economist Dana Saporta.

“Anytime you see something that hasn’t happened since the last quarter of 2008, it’s worth noting,” Saporta said in a phone interview. “It may be that this is an interesting oddity but if we continue to see this it could reflect a more broad- based nervousness on the part of household investors.”

Withdrawals from equity funds are usually accompanied by an influx of money to bonds, and an exit from both at the same time suggests investors aren’t willing to take on risk in any form. While retail investor sentiment isn’t the best predictor of market moves, their reluctance could have significance, Saporta said.

“It might suggest households are getting nervous about holding investments, and that could lead to some real economic implications including cutting back on spending,” she said. “Should the market turn lower again, it will be interesting to see if we have the traditional move back into bonds or if households move to cash.”

After an 11 percent plunge in the Standard & Poor’s 500 in the past week, investors are searching for signs of strength in the U.S. economy in the face of slowing growth abroad. The S&P 500 gained 2.4 percent Thursday as data showed gross domestic product rose at a 3.7 percent annualized rate, exceeding all estimates of economists surveyed by Bloomberg.

While the flows out of mutual funds suggest retail investors -- who held 89 percent of U.S. mutual fund assets last year, according to ICI -- may not have faith in financial markets, recent economic data show the average American is spending more. Sales at U.S. retailers rose 0.6 percent in July and the prior two months were revised up, according to Commerce Department data on Aug. 13.