Sprint Nextel Corp. said Tuesday that it would buy outstanding shares of Nextel Partners Inc. in a deal valued at $6.5 billion, or $28.50 per share, settling a battle with its largest affiliate.

Nextel Partners shareholders had approved a provision in October that required Sprint Nextel to buy two-thirds of the company it doesn’t already own. Including the one-third shares that Sprint Nextel already owns in the affiliate, the deal puts the value of Nextel Partners at about $10 billion.

Sprint Nextel and Nextel Partners engaged in a monthslong fight over the value of the affiliate, which is based in Kirkland, Wash. Sprint Nextel is based in Reston, Va., and has operational headquarters in Overland Park.

Shares of Sprint Nextel closed down 17 cents at $24.47 in trading on the New York Stock Exchange. Shares of Nextel Partners closed up $1.52 at $27.84 in trading on the Nasdaq Stock Market.