From Reuters via Yahoo Finance:
The pick is a controversial one for the financial services sector, where many bankers have criticized her as an overzealous regulator bent on punishing Wall Street and who does not fully understand the financial system. She has called for the breakup of the largest banks ...
Warren would also be able to forcefully push for financial regulators to use all the powers available to them to write strict interpretations of rules. That could mean stronger curbs on Wall Street trading, higher capital buffers and rules that would compel mega-banks to shrink.
Warren is the architect of the new Consumer Financial Protection Bureau, an agency created by Dodd-Frank in 2010. Although she helped set up the new government watchdog,[the] President refrained from nominating her as its first director, because of fierce opposition in the Senate.