The day after Lehman Brothers Holdings Inc. declared the largest bankruptcy in U.S. history in 2008, Federal Reserve officials remained unsure whether the financial crisis would do lasting damage to the U.S. economy, Bloomberg News reported yesterday. “I don’t think we’ve seen a significant change in the basic outlook,” Dave Stockton, the Fed’s top forecaster, said on Sept. 16, 2008, according to transcripts released on Friday. “We’re still expecting a very gradual pickup in GDP growth over the next year.” The records show Fed officials struggling to understand the magnitude of the financial crisis that was underway, and the potential fallout for the economy. At the September meeting, officials discussed the collapse of Lehman, yet left their main interest rate at 2 percent, rebuffing calls by some investors for an immediate cut.