Gallagher joined the Division of Trading and Markets in 2008. Gallagher played a key role in the SEC’s response to the financial crisis. He oversaw the issues arising from the bankruptcy of Lehman brothers, rulemaking to address issues regarding credit rating agencies, and efforts to facilitate the central clearing of credit default swaps. He earned his law degree, magna cum laude, from Catholic University of America and graduated from Georgetown with a BA in English.