Mary-Kate, Ashley, Swagger

Mary-Kate Olsen rides her horse, Swagger, while competing in the Hampton Classic Horse Show on Thursday (August 28) in New York City.

While relaxing on the sidelines, MK showed off her large engagement ring from fiance Olivier Sarkozy.

Ashley is also in the Hamptons this week and they have been spotted roaming around town on several occasions over the last few days.

Ashley Olsen making a swift exit out of her office in the West Village neighborhood of New York City (August 27):

JustJared says this is Ashley stopping by Hampton Classic Opening Day with some friends, but I'm pretty positive this is Mary-Kate.

SourceS: 1, 2