NEW YORK CITY-Equity Residential, which unsuccessfully sought control of Archstone Enterprise LP earlier this year, will end up with the lion’s share of its multifamily rival after all. Equity, based in Chicago, and Arlington, VA-based AvalonBay Communities Inc. said late Monday afternoon that they’re acquiring Archstone’s assets and liabilities for a total of $16 billion, including the assumption of $9.5 billion in debt. The seller is locally based Lehman Brothers Holdings, the estate of the investment bank that filed the largest bankruptcy in history four years ago. Bloomberg first reported the story Monday afternoon.

“Archstone’s assets will fit perfectly into the Equity Residential portfolio, further improve the overall quality of our assets and add scale to our operating platform in our core markets,” David J. Neithercut, Equity’s president and CEO, says in a statement. He adds that by funding much of Equity’s 60% acquisition of Archstone with proceeds from the sale of assets in non-core, exit markets, “we are accelerating the completion of the total transformation of our portfolio. As a result, Equity Residential’s future earnings and shareholder return will be derived from the highest quality assets in the nation’s high-barrier, high-growth coastal markets.”

For his part, Tim Naughton, AvalonBay’s CEO and president, says in a separate statement, “This acquisition accelerates our strategic growth vision of more deeply penetrating our core, high barrier-to-entry coastal markets. This is a rare opportunity to acquire a high quality portfolio of apartment communities concentrated in our markets, to better achieve our geographic portfolio allocation goals, to enhance operating efficiencies and to further advance our multi-brand strategy.”

The deal encompasses more than 45,000 apartment units and is expected to close in the first quarter of 2013. will provide more detail on the Archstone deal tomorrow.