The Federal Deposit Insurance Corp.’s deposit insurance fund, which protects customer holdings up to $250,000 per account in the event of a failure, was positive for the first time in two years, the agency said. The fund, which had been depleted by a wave of bank failures stemming from the collapse of the U.S. housing market, rose to $3.9 billion because of fewer expected bank failures and assessment revenue, the agency said. The FDIC insures deposits at more than 7,500 banks and thrifts. Lenders put aside 53 percent less money to cover bad loans, and charge-offs dropped 42 percent. The $20.9 billion decline in charge-offs was the largest since the recovery in credit quality began, the FDIC said.