Equity Residential (EQR) said Tuesday it may sell up to 17 million shares into the market in the next three years, giving the country's largest apartment dwelling developer and manager easy access to capital for future investments.

Friday, Moody's Investors Service cut its outlook on the real-estate investment trust to negative because of its high debt levels compared to profit, which has been falling on lower property sales. Equity Residential said money from the offering, in addition to funding the purchases and development of multifamily properties, may be used to help pay down debt.

The REIT also trumpeted its liquidity - as Moody's had done the previous week - by noting it has more than $800 million of cash, $1.36 billion available under its credit facility and the ability to sell noncore assets.

Equity Residential has about 273 million shares outstanding. Its shares closed Monday at $31.46 and weren't active premarket. Shares are up 6% so far this year, having doubled from a low in March.

-By Joan E. Solsman, Dow Jones Newswires; 212-416-2291; joan.solsman@dowjones.com