jamie selway lead candidate head u.s. securities exchange commission division trade market withdraw name consideration accord person direct knowledge matter trade market job one last major position new sec chairman jay clayton still fill unit oversee securities exchange market broker-dealers clear agencies derivatives financial industry regulatory authority selway head execution service agency brokerage investment technology group inc make decision four months name float front runner position reason delay clear selway immediately available comment widely respect expert equity market structure selway co-founded institutional agency broke white cap trade 2003 board exchange operator bat own cboe hold 2008 2015. selway withdrawal first report wall street journal itg 's selway drop run key sec job