Steven A. Cohen built a reputation as a fast trader with an uncanny ability to predict where stock prices are headed. He’s applying his investing style to an art collection that now accounts for about $1 billion of his $11 billion fortune. Cohen is selling two paintings estimated at more than $65 million at New York auctions this month, according to people familiar with the matter, as the billionaire money manager is taking advantage of surging prices. The works are part of the bellwether semiannual auctions at Sotheby’s, Christie’s and Phillips that will target more than $2.1 billion in sales over 10 days starting Wednesday. The 59-year-old Cohen regularly sells pieces from his collection, both privately and at auction, and buys new ones, according to dealers and advisers.