Mark Cuban, who made billions from the dot-com bubble, says here's how you'll know the rally is over

Key Points
  • Billionaire Mark Cuban said the stock market's valuation doesn't remind him of 1999's dot-com boom.
  • "I think interest rates will tell us what's going to happen next in the market," Cuban told CNBC.
  • "Is it frothy? You can definitely make that argument. Is it like 1999? No," he said.
Market not like 1999: Mark Cuban disagrees with Paul Tudor Jones

Mark Cuban, who made billions of dollars during the dot-com boom, said Wednesday that the stock market is not reminiscent of 1999.

"Interest rates were a lot different back then," Cuban said on CNBC's "Fast Money Halftime Report." "And you saw a lot more people participating in the market. ... You don't see that now. That individual day trading really led the market to be frothy."

The levels of day trading have receded and given way to the rise of index funds, creating a fundamentally different landscape, Cuban said.

"There's so much money chasing index funds, so as long as those funds keep on growing the market is going to go up," said Cuban, who sold to Yahoo in April 1999 for $5.7 billion.

Cuban's comments Wednesday were in response to concerns from investors who are comparing the stock market's current valuation to the bull market in 1999 that concluded with collapse of the dot-com bubble.

Highly speculative internet stocks helped propel the tech-dominated Nasdaq up more than 500% from 1995 until the bubble burst in March 2000.

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On Tuesday, for example, billionaire investor Paul Tudor Jones called the stock market "crazy."

"We are just again in this craziest monetary and fiscal mix in history. It's so explosive. It defies imagination," Jones said on CNBC's "Squawk Box" at the World Economic Forum in Davos, Switzerland.

"It reminds me a lot of the early '99. In early '99 we had 1.6% PCE, 2.3% CPI. We have the exact same metrics today," he continued.

But like Cuban, Jones noted the difference in interest rates in 1999 and 2020. In the early half of 1999, the Federal Reserve had set interest rates at 4.75%. They are currently 1.5% to 1.75%.

In fact, Cuban, who owns the NBA's Dallas Mavericks, said interest rates will ultimately determine the fate of the stock market, which continues to move toward the upside in 2020 after a strong 2019.

The S&P 500 is up around 3% year to date and its 29% gain in 2019 was its best annual performance since 2013.

As long as rates stay this low, Cuban said, "Where else are you going to put your money?"

"So that money is going to continue to flow into our equities, our market," Cuban said, while borrowing a phrase used by his friend who compared low interest rates to universal basic income "for rich people."

"I think interest rates will tell us what's going to happen next in the market. Is it frothy? You can definitely make that argument," Cuban said. "Is it like 1999? No."

- CNBC's Yun Li contributed to this report.

Disclosure: CNBC owns the exclusive off-network cable rights to "Shark Tank," on which Mark Cuban is a co-host.

Why Paul Tudor Jones says the markets remind him a lot of early 1999