Dallas Mavericks owner Mark Cuban watches on from behind the bench during the second half of an NBA game against the Atlanta Hawks at State Farm Arena on February 22, 2020 in Atlanta, Georgia.

Billionaire entrepreneur Mark Cuban isn't convinced that the swift market rally is here to stay.

"I'm surprised. I think this is kind of buy the rumor and potentially we sell the news when reality sets in," Cuban said Wednesday on CNBC's "Closing Bell." "I think people are naturally optimistic right now in terms of the market. I just don't think they are really factoring in what we are going to see on the other side."

Cuban, owner of the NBA's Dallas Mavericks, revealed that he hasn't bought any stocks in two weeks and is "trying to get more cash."

The market bounced sharply in the past two weeks, with the S&P 500 jumping 25% from its 52-week low of 2,191.86 on March 23. Investors are betting on a turnaround ahead for the coronavirus crisis as cases in some of the hardest-hit regions began to show signs of slowing.