Three of Sprint Nextel's (NYSE:S) senior executives resigned from Clearwire's (NASDAQ:CLWR) board in what Clearwire said was an "abundance of caution to address questions raised by Clearwire regarding new developments in antitrust law." Sprint CEO Dan Hesse, Steve Elfman, president of network operations and wholesale, and Keith Cowan, president of strategy and corporate initiatives, resigned from the board. Sprint, which holds a 54 percent stake in Clearwire, has the right to appoint seven of the company's 13 directors, and the company plans to appoint independent successor directors in the coming months. The Sprint executives' departure also raises speculation about the future of Clearwire, including whether Sprint will buy Clearwire outright, or whether Clearwire will strike a deal with No. 4 carrier T-Mobile USA. Article (sub. req.)