(Recasts; Adds details, share move)
* American Tower to pay $304 mln in cash to Unison Holdings LLC
* Says to assume about $196 million in debt
* Sees deal closing in Q4
Sept 7 (Reuters) - American Tower Corp said it agreed to buy 1,800 sites for communication towers from Unison Holdings LLC for about $304 million in cash.
American Tower will also assume about $196 million in debt.
The acquisition is expected to close in the fourth quarter, the wireless tower operator said in a regulatory filing.
American Tower, which manages about 38,000 towers around the world, has been buying up towers in the U.S. and also expanding its footprint in emerging markets.
In July, the company agreed to buy 2,126 telecom towers in Colombia from Colombia Móvil, a unit of Millicom International Cellular S.A. , for $182 million in cash.
Shares of the Boston-based company were trading up 1.5 percent at $53.82 in morning trade on the New York Stock Exchange. (Reporting by Supantha Mukherjee in Bangalore; Editing by Sriraj Kalluvila and Joyjeet Das)