Softbank Corp. and Sprint Nextel Corp. have entered into definitive agreements under which Japan's third-largest mobile phone carrier will pay $20.1 billion (about ¥1.57 trillion) to acquire a 70 percent stake in the No. 3 U.S. cellphone firm, Softbank said Monday.

The deal would create one of the leading communications groups in the world, boasting 90 million mobile phone subscriptions.

Softbank will pay $12.1 billion, or about ¥946.9 billion, to Sprint shareholders and the deal includes $8 billion, or ¥624 billion, in new capital, the company said.