Costco Falls After Reporting Problem With IT Systems in Results

Costco Wholesale Corp.’s information-technology problem, which roiled its bookkeeping and sent the stock tumbling on Thursday, was tied to workers getting access to financial data after they should have been cut off.

While a company official was cryptic on their call with analysts, Costco later said that it has hired outside experts to check for any signs of meddling. Earlier, in its report for the latest fiscal quarter, Costco said it expects to disclose “material weakness in an internal control” related to user access to the systems that support the “financial reporting process.”