The acquisition, which follows Google's recent US$3.1bn purchase of DoubleClick, is described by Yahoo as "a key step" in its long-term online advertising strategy.
Yahoo bought a 20 percent stake in Right Media in October 2006, and will acquire the remaining equity interest for approximately US$680m.
Shareholders will be paid in approximately equal parts cash and stock, and Right Media options and similar equity awards will be assumed by Yahoo.
The move will help "democratise" the buying and selling of digitally-enabled advertising, according to Yahoo chairman and chief executive Terry Semel.
"This acquisition is an important step in our long-term vision to build the industry's leading advertising and publisher ecosystem," he said.
Yahoo will increase its participation in the Right Media Exchange both as a buyer and seller.
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iTnews Executive Retreat - Security Leaders Edition
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