It plans to pay for another half of the purchase with its own stock.
The four banks are also advising Verizon, along with former Morgan Stanley banker Paul Taubman and Guggenheim Partners, the sources said.
Goldman Sachs and UBS are advising Vodafone, the sources said.
Verizon Communications and Vodafone declined to comment. Goldman Sachs declined comment, as well. The other banks were not immediately available for comment.
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Under the terms of the deal, Verizon Communications will buy Vodafone's U.S. holding company, Vodafone Americas, that owns the Verizon Wireless stake and some other assets, the sources said.
Verizon will then keep the Verizon Wireless stake and sell European assets back to Vodafone, in a move that is expected to reduce Vodafone's tax bill to around $5 billion, the sources said.
The deal marks the third-largest acquisition announcement in corporate history and British telecom giant Vodafone's exit from the large but mature U.S. market.