EarthLink ( ELNK) boosted its share buyback plan by $100 million. The Atlanta-based Internet service provider said the expansion comes on top of an existing $45 million share-repurchase authority. The company has bought back nearly 14 million shares under a previous program. The company also said it would buy back shares in connection with so-called Rule 10b5-1 plans, which allow officers to sell stock on a predetermined quarterly schedule. On Monday, the stock was flat at $9.22.