Mohamed El-Erian, chief executive officer of Pacific Investment Management Co., said the Federal Reserve’s policy of unprecedented asset purchases added 0.25 to 0.5 percentage point to gross domestic product.

“Most people agree that the impact on the real economy has been disappointing,” El-Erian said during an interview on Bloomberg Television’s “In the Loop” with Betty Liu. “But the impact on financial assets has been quite considerable.”

The U.S. central bank has been buying $85 billion of Treasurys and mortgage securities a month since January to keep borrowing rates low and spur economic growth.

The Fed’s first step may be tapering monthly debt purchases in September by $10 billion, according to the median estimate of analysts in a Bloomberg survey concluded this month.

Investors need to consider when the Fed will start to pare asset purchases and how they will taper, as well as the global implications, El-Erian said. The central bank will probably reduce its Treasury purchases rather than mortgage bonds, he said.