Stamps.com shares dipped almost 50% in late trading on Thursday after the company said it was giving up its exclusive deal with the U.S. Postal Service reports Marketwatch.“We will no longer be exclusive to the USPS and that’s non-negotiable,” Chief Executive Kenneth McBride said of demands his company made in negotiations to renew their revenue-sharing agreement. “The USPS has not agreed to accept these terms or any other terms of our partnership proposal. So at this point we’ve decided to discontinue our shipping partnership with the USPS so that we can fully embrace partnerships with other carriers who we think will be well-positioned to win in the shipping business in the next five years.”Following the announcement the shares continued to dive and were recently down nearly 48% in after-hours trading.McBride later stressed that Stamps.com will still be able to sell stamps. “Note that our decision to discontinue our exclusive partnership with the USPS does not in any way impact our regulatory relationship with them or the products and services we are able to offer our customers,” he said, stressing that the move is an effort to service other carriers such as FedEx, UPS and Amazon.comInc.