Mark Cuban's best investing advice: 'Don't'

Tim Sharp/Reuters

Billionaire Mark Cuban doesn't mince words.

When Entrepreneur asked him on the set of "Shark Tank" for his best advice to make money investing, he replied: "Don't." 

"The market could go up for years, and you could think you're well off," he told Entrepreneur, "and then, in a millisecond with high-frequency trading, a flash crash can take it all away. That's why you want to have that money in the mattress, that savings, so you're protected in case something goes wrong."

The "money in the mattress" he's referring to is a six-month emergency fund that he recommends everyone gather. Experts advise keeping three to nine months' worth of living expenses in an easily accessible, untouched account in case of an emergency. "I know it doesn't earn much in the bank," Cuban told Entrepreneur, "but you'll sleep a lot better."

However, Cuban's investing advice isn't the same given by most financial pros. While the consensus is that the ordinary person shouldn't take on undue risk in order to try and "beat the market," most agree that some exposure to the market, at the very least in the form of retirement accounts, is necessary to keep your money growing fast enough to beat inflation.

Low-cost index funds (a type of mutual fund pegged to a specific market index) are also regularly recommended by some of the wealthiest people around. Experts such as Warren Buffett, Charles Schwab, John Bogle, and Charlie Munger agree that low-cost index funds are the best way for the average person to invest.

"A low-cost index fund is the most sensible equity investment for the great majority of investors," Buffett told Bogle in "The Little Book of Common Sense Investing." "By periodically investing in an index fund, the know-nothing investor can actually out-perform most investment professionals."

Whether you feel comfortable investing, Cuban's advice on putting together an emergency fund before making any other major decisions with your money is echoed by most experts. Looks like it's time to start saving.

Kathleen Elkins contributed reporting.

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