Hedge fund billionaire Ken Griffin cautions any wary investors that the current bull stock market is far from over.

"If we look at history we're not yet at the end of this business cycle,” Griffin, the CEO of Citadel, a hedge fund managing more than $26 billion, told CNBC.

“What's somewhat disturbing thought is we're getting closer to that moment in time. And we're getting closer to that moment in time with yet an enormous amount of accommodative monetary policy," Griffin told CNBC's "Power Lunch."

"I think this business cycle has further to go and I think the stock market's going to go with that," Griffin said. "But what's worrisome is the firepower that we have to address the next downturn is somewhat constrained. That should worry all of us."

U.S. stocks haven't fallen more than 20 percent from a recent high since March 2009, marking the second-longest bull market in history, CNBC.com explained.

Investors' stock-market bets that President Donald Trump can implement his pro-business agenda are partly behind a rally that has taken stock indexes to record highs.

Griffin isn't alone in his optimistic outlook on the market.

Professional investor and media analyst Jon Najarian also told Newsmax TV that the stock bull market that has basically been raging since Trump’s election has enough energy to surge as much as 10 percent more despite some looming “bumps” on the road to more record highs.

“The Trump bump can still run,” Najarian told Sunday’s “The Income Generation Show.”

“In the short term, there's going to be those bumps that could cause either (Fed Chair Janet) Yellen or the economy to pause and when we hit those, I don't think we see 10 percent corrections. But I do think that we can go up another 7-10 percent this year so again with an eight or nine-month timeframe,” he told host David J. Scranton.

“I'd say more upside than downside,” he predicted.

He also sees the economy gaining some strength amid the regulation rollback and the likelihood that we're going to see taxes decreased as well for individuals and corporates, said Najarian, who with his brother Pete are the co-founders of OptionMonster.com and he's a regular on CNBC's "Fast Money."