Mary-Kate Olsen is a budding equestrian. The pint-sized designer and former actress’ horse Marvelous won section B in the Local Hunter sections at the Hampton Classic this weekend. James Anderson rode Marvelous in the competition, but Olsen was there on her mount, decked in full riding gear, to accept the award, something we’re told is normal practice and “nothing snotty.” She was also spotted on the grounds with her French banker boyfriend Olivier Sarkozy. We’re told Olsen rides in other competitions but doesn’t jump. Also competing yesterday and today is Billy Joel’s girlfriend Alexis Roderick.