Stamps.com Inc. /zigman2/quotes/202777086/composite STMP -0.02% said Monday afternoon that it planned to repurchase up to $60 million in shares after a massive decline. The company said that the board of directors authorized the company to buy back shares over the next six months, starting March 14. Shares in the online-postage company dove more than 50% after executives announced the end of an exclusive deal with the U.S. Postal Service last month, leading to a dismal forecast for 2019. Shares gained almost 2% in after-hours trading, after closing up 1.4% at $88.31.