For years, Macy’s Inc. touted its ability to boost profits by cutting delivery costs and trimming other expenses on calls with Wall Street analysts. Then on Monday, the department store chain surprised investors by revealing that those very costs had become the source of an internal investigation into what the company has described as a multimillion-dollar employee plot to manipulate the metrics.

The employee "intentionally made erroneous accounting accrual entries" to hide millions of dollars, Macy's said. The error forced the company to delay reporting its third-quarter results.