Lululemon Athletica Inc. said late Thursday it has agreed to buy back 3.3 million of its shares in a private transaction with funds affiliated with Advent International Corp. The shares will be repurchased under the company's recently increased $600 million share buyback program, and funded with cash on hand and borrowing, Lululemon said. Advent also has told Lululemon that it has sold an additional 6.7 million shares of the company's stock. "Today's partial sale is consistent with our planned monetization of our interest in Lululemon.