RESTON (WiMAX Day). After weeks of speculation, Sprint Nextel and Clearwire announced today that they “plan to jointly construct the first nationwide mobile broadband network using WiMAX technology, and promote the global development of WiMAX-based services.”

The joint venture is expected to enable both companies to deploy their networks faster, and will “enable each company to increase capital efficiency and reduce overall network development and operating costs.”

In a conference call with investors this morning, Sprint Nextel chairman and CEO Gary Forsee said the joint venture would deliver “meaningful savings” for both companies. The joint venture will operate on a roughly 70/30 basis, with Sprint contributing the majority. For Sprint this eases the cost of building a network alone.

The companies plan to build their respective portions of a nationwide network, and will enable roaming between their two networks. The companies also will swap some of their 2.5 GHz spectrum “in order to optimize build-out, development and operation of the network.”

The immediate cost benefit of this joint venture will result from Sprint and Clearwire working together jointly on the evolution of products and services, sharing infrastructure, as well as marketing and distribution.

Forsee added in the call this morning that the joint venture would provide Clearwire with access to Sprint’s technical facilities, including broadcast towers, fibre network, and backhaul services. The joint venture also will realise significant savings from joint purchasing of WiMAX equipment.

Clearwire CEO Ben Wolff said that the arrangement will enable the two companies to use their “respective spectrum more efficiently than either company could have on its own.” It will also help each company focus on specific markets, according to Wolff, in a way that is mutually beneficial to both sides.

In a startling move, the companies also said that they will market WiMAX services under a common brand name, and will share retail distribution channels. Sprint will “take the lead” in working with strategic partners, MVNO deals and working with distributors.

The two companies will build their networks to reach some 100 million people by the end of next year. Sprint also said that it remains on course for the initial launch of its network at the end of this year.

While Sprint and Clearwire have indicated they will act fast to execute definitive agreements within 60 days, the joint venture is also subject to review by the US Justice Department. In addition, a transfer or assignment of either company’s spectrum will require approval by the US Federal Communications Commission.

Neither company expects delay in government approval, as the benefits are clear for all industry stakeholders. The joint venture is monumental for the WiMAX industry, and investment analysts welcomed the news.