Telecommunications giant Sprint Nextel Corporation on Tuesday said that it agreed to acquire Virgin Mobile USA Incorporated in a stock deal valued at $5.50 per share in a bid to expand its prepaid cell phone offerings. Sprint valued the deal at $483 million, including Sprint's existing 13.1 percent stake in Virgin Mobile. The transaction represents a 31 percent premium to Virgin Mobile's Monday closing share price of $4.21. When the deal closes, Sprint will retire Virgin Mobile USA's outstanding debt, which is expected to be no more than $205 million on September 30. The deal allows Sprint to expand its prepaid cell phone offerings, bringing together the Virgin Mobile brand with its current Boost Mobile business.