WASHINGTON — Sens. Elizabeth Warren, D-Mass., and Bernie Sanders, I-Vt., are raising concerns about why independent audits of Wells Fargo's internal controls didn't discover fraudulent account openings by thousands of employees.

The two lawmakers, along with Sen. Mazie Hirono, D-Hawaii, sent a letter Thursday to the accounting firm KPMG asking about its reviews of Wells' internal controls between 2011 and 2015.

"KPMG conducted audits assessing Wells Fargo's internal control over its financial statements…But none of KPMG's audits identified any concerns with illegal behavior that resulted in the creation of over two million unauthorized accounts by thousands of employees," the senators wrote in the letter to Lynne Doughtie, chairman and chief executive Officer of KPMG. "In fact, in each of your audits, your firm concluded that Wells Fargo 'maintained … effective internal control over financial reporting.' "

The senators asked Doughtie to answer a number of questions, including whether KPMG knew about the more than 2 million accounts that were created for customers without their knowledge, whether Wells misled the firm, if KPMG stands by its audits and if the firm has faced any disciplinary action from the Public Company Accounting Oversight Board.

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