NEW YORK/BANGALORE Billionaire investor Ken Griffin, founder of U.S. hedge fund Citadel, said on Thursday that he has some doubts about the continuity of the markets rally and is concerned about the about the U.S. fiscal situation.

"I'm a bit anxious that this rally can continue," he said in an interview on CNBC. "I like to believe that this rally has legs. I'm a bit anxious. We're sort of in the seventh or eighth inning of this rally, but part of it has been the soft landing story."

The S&P 500 stock index is up 16.8% this year, in a rally mainly driven by optimism around artificial intelligence.

Griffin said the Federal Reserve is likely close to the end of the interest rate hiking cycle in its battle to tame inflation. "There's a small chance of one more increase later this year," he said.

Still, he said it is unclear when Fed chair Jerome Powell will be able to cut rates because of some ongoing stimulus measures.

"He's showing up in a fight with both of his hands tied behind his back because D.C. is just on a different agenda than he is," Citadel's founder said. "He's trying to prudently slow the economy, bring inflation back down and really engineer the whole soft landing."

Gasoline prices are also a concern to inflation, as prices have risen.

Griffin considered it is unlikely that inflation will come down to the Fed's 2% target. "It only will be at 2% if the economy is in a real recession."

Citadel, which invests $61 billion for clients, became the most successful hedge fund of all time last year when it earned $16 billion.

(Reporting by Jahnavi Nidumolu, in Bangalore and Carolina Mandl, in New York; Editing by Chizu Nomiyama)