Widely seen as the bank's answer to complying with the fiduciary rule, 61 percent of advisors have at least half of their client assets on the platform as of this month, the bank said.

Thiel's tenure was also defined by the cultural shift following the bank's 2009 acquisition of Merrill Lynch, where the firm changed from Wall Street's "thundering herd" to a small slice of a big commercial bank. Some brokers chafed as Bank of America raised new client account minimums to $250,000 worth of assets and prodded them to refer business to other parts of the bank.

Thiel's personal focus on wellness also bled into the broader firm, with health gurus leading brokers in aerobics exercises and urging healthy eating.

Bank of America Chief Executive Brian Moynihan has praised Thiel's leadership of Merrill Lynch in quarterly earnings calls, as the global wealth and investment management business's pre-tax profit margins rose from 9.9 percent in the fourth quarter of 2011 to 26 percent in the second quarter this year.