American Tower Corp. (AMT) announced plans to sell six-year senior unsecured notes to institutional investors through a private placement, using the proceeds to pay off other debt.

Possibilities include the redemption of notes due 2012 at a price of 101.781% of face value, plus accrued and unpaid interest. Companies of all stripes have been selling debt and/or stock in recent months, with many putting the proceeds toward leverage reduction.

American Tower, which operates cellphone towers, didn't disclose how much of the new notes it might sell.

The company last week was raised to investment-grade territory by Moody's Investors Service, which cited American Tower's market position and disciplined growth initiatives. The ratings agency said demand for the wireless tower sector was likely to remain favorable through the next several years and it expects American Tower's market position to help boost earnings momentum.

Shares closed Monday at $37.73 and were inactive premarket. The stock is up 29% this year.

-By Kevin Kingsbury; Dow Jones Newswires; 201-938-2136; kevin.kingsbury@dowjones.com