Well, it looks like T-Mobile is no longer on friendly enough terms with Radio Shack to call it "The Shack." The retailer announced today that it's ending its partnership with the carrier in favor of a new one with rival Verizon, which will be joining current partners AT&T and Sprint. The last day to buy a T-Mobile phone or service plan at The Shack will be September 14th, with Verizon moving in and setting up shop the very next day. As Reuters notes, however, the move isn't all that surprising -- the partnership has apparently been both an unprofitable one and a rocky one, with Radio Shack recently alleging that T-Mobile had "materially breached" its contract. While that's a bit of a blow for T-Mobile, the move seems to be working out quite well for Radio Shack -- its stock has already shot up more than 20 percent today on the news.