MetLife Inc. said that roughly 13,500 workers were left without their monthly retirement benefits over the past quarter century because of a records mistake, the first time the insurance giant disclosed the specific number of people affected by the pension snafu, the Wall Street Journal reported. In a regulatory filing on Tuesday, MetLife attributed the problems to a policy established 25 years ago to contact would-be pension recipients twice, rather than employing aggressive search techniques to track down people and make them aware of their eligibility for monthly income. It then shrank balance-sheet reserves that reflected MetLife’s payment obligation to these people. The company also said it lacked a system under which details about the missing payments were escalated throughout the company. At least some top executives, the company has previously said, didn’t become aware of the problems until last fall.