Citadel's Griffin worried about next U.S. market downturn -CNBC

NEW YORK, June 7 (Reuters) - Ken Griffin, founder and chief executive of hedge fund firm Citadel LLC, said Wednesday that the run-up in the U.S. stock market was not over, but that he was concerned about the ability to address the next downturn.

"I think this business cycle has further to go. I think the stock market is going to go with that, but whats worrisome is: the firepower that we have to address the next downturn is somewhat constrained," Griffin told cable television network CNBC. (Reporting by Sam Forgione; Editing by Lisa Shumaker)