PayPal Holdings Inc. PYPL, +2.49% said late Friday it has found evidence of a data breach in TIO Networks, a payment processing company PayPal bought in July. The unauthorized access could have compromised "personally identifiable information" for approximately 1.6 million customers, including TIO customers and customers of TIO billers. PayPal said the its platform was not impacted, as the TIO systems run separate, PayPal's customers' data remains secure. PayPal halted TIO operations on Nov. 10 as part of an ongoing investigation. The company said it has begun working with the companies it services to notify potentially impacted people, and with a consumer-credit reporting agency to provide free credit monitoring memberships for those affected. People involved in the data breach will be contacted directly and receive instructions to sign up for monitoring, PayPal said. Shares of PayPal were flat in late trading after ending the regular session down 0.6%.