The U.S. Federal Reserve should consider buying Treasury bills in the next phase of its balance-sheet program, said Boston Fed President Eric Rosengren. In a speech to the Credit Suisse Asian Investment Conference early Tuesday morning in Hong Kong, Rosengren said that one way to stimulate the economy in a "hypothetical" recession would be to push down long-term interest rates by selling Treasury bills from the bank's balance sheet. The only problem is that the Fed holds virtually no T-bills at the moment. "Thus, increasing the share of U.S. Treasury bills and more quickly lowering the duration of securities held [by the Fed] as assets may be an important part of the normalization process," Rosengren said. The Fed has been shedding assets from its balance sheet for almost two years but announced last week that this process will end in September. At some point next year, economists think the central bank will begin buying assets again. The Fed has not agreed yet on what mix of T-bills, or Treasury notes and bonds it might buy when that process starts.