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Former Yahoo CEO Marissa Mayer will testify before a Senate committee on Wednesday regarding the massive data breaches that occurred under her watch. However, she only agreed to do so after the committee compelled her appearance with a subpoena, according to reports.

A spokesperson for the Senate Commerce Committee confirmed to ZDNet that the committee issued a subpoena. However, a representative for Mayer told the Hill that she is appearing before the committee voluntarily. The spokesperson did acknowledge to the Hill that the former CEO initially suggested she was not the best witness to discuss the data breaches, which compromised billions of Yahoo accounts.

Along with Mayer, multiple other former and current executives will testify at Wednesday's hearing on data breaches, including Karen Zacharia, deputy general counsel and chief privacy officer at Verizon (which acquired Yahoo in June); former Equifax CEO Richard Smith; interim Equifax CEO Paulino do Rego Barros, Jr.; and Entrust Datacard CEO Todd Wilkinson.

In September 2016, Yahoo disclosed the theft of 500 million records, then thought to be the largest theft of records in history. Just a few months later, the company revealed a separate theft of one billion records. Then just last month, the web giant said that effectively all 3 billion Yahoo user accounts had been affected by the 2013 breach. After Verizon's acquisition of Yahoo was finalized in June, Mayer stepped down from the company.