EXCHANGES-SUMMIT/A bit grayer and world wearier, maybe, but there’s no mistaking the family resemblance between NYSE Chief Operating Office Larry Leibowitz and his kid brother Jon Stewart. Unlike the Daily Show host, Leibowitz mostly keeps a low profile, although he did find himself in the spotlight even before his appearance at the Reuters Global Exchanges and Trading Summit on Monday. The Wall Street Journal interviewed him in a story about the NYSE’s effort to turn some high frequency traders — who have been chipping away at the exchange’s business — into exchange floor traders.