Billionaire investor Howard Marks on stocks: 'This is not the time to take on more risk'

  • Oaktree Capital's Howard Marks shares his market views on CNBC's "Halftime Report" Tuesday.
  • He cautions investors about the market's high valuation.

Howard Marks warned investors about putting more funds in the stock market at its current level.

"We are living in a low-return world, characterized by significant uncertainty," Marks said on CNBC's "Halftime Report" Tuesday. "This is not the time to take on more risk. Things have been going awful well for almost 10 years. That's not the time to turn up the wick."

The investor noted the market's strong performance of a nearly 25 percent return in the past 12 months and the historic low levels of volatility. He said some of the tax cut bill's benefits may already be discounted in the rally.

"Is [the market] a bargain? Unlikely," he said.

The Oaktree Capital co-chairman also cautioned his investors last week over the market's elevated valuations.

"Most valuation parameters are either the richest ever … or among the highest in history," Marks wrote in a note to clients Jan. 23. "In the past, levels like these were followed by downturns. Thus a decision to invest today has to rely on the belief that 'it's different this time.'"

Marks is known for his prescient investment memos, which warned about the financial crisis and the dot-com bubble implosion.

Oaktree Capital had $100 billion of assets under management as of December 2017, according to its website.