Watch CNBC's full interview with Pershing Square CEO Bill Ackman

Bill Ackman, CEO of Pershing Square, joins CNBC's 'Squawk Box' to discuss his outlook on the U.S. economy, inflation, the Fed, and more ahead of the open on Tuesday. "I think the biggest problem for the economy is inflation," Ackman tells CNBC. "And unfortunately, the steps taken by the Federal Reserve have not been effective."