We study how financial intermediary external oversight affects managerial self-dealing. Following an increase in external scrutiny of broker-dealers in the early 2010s, we document a decline in the backdating of executive stock gifts. This reduction amounts to approximately \$100,000 in lost tax benefits per executive annually. Treatment effects are stronger for broker-dealers with weaker pre-existing controls, those offering more complex financial services like financial planning, and those with previous misconduct history. Our findings highlight how intermediary oversight can serve as a mechanism for curbing private benefit extraction, complementing direct regulation of corporate insiders.