Memphis-based real estate investment trust MAA has completed its $4 billion merger with rival Post Properties Inc., creating a combined company with an equity market capitalization of about $11 billion and overall market cap of $15 billion.

"We have successfully completed early integration activities and are off to a great start,” Eric Bolton, MAA chairman and CEO, said in a statement Thursday, Dec. 1, announcing the deal’s closing. “We look forward to completing the integration work over the coming year and positioning to capture the full range of opportunities surrounding the merger."

Shareholders of both companies had approved the merger on Nov. 10.

The company will retain the name MAA, formerly called Mid-America Apartment Communities Inc., and will trade under the existing NSYE ticker symbol MAA.

In an unrelated development, MAA was added to the S&P 500 Index at the close of business Thursday.

The MAA board of directors will expand from 10 to 13 members with the merger. The new members are David P. Stockert, former president and CEO of Atlanta-based Post Properties, and Russell R. French and Toni Jennings, former directors of Post.

Bolton will continue to serve as CEO and chairman of the board.

The merger is anticipated to save the combined company approximately $20 million in overhead costs and the elimination of duplicative costs associated with being separate public companies. The enhanced scale of the company and leveraging of technology and operating systems is expected to improve operating margins as well, MAA said in the release.

These savings and enhancements are expected when the companies are fully integrated, which is estimated to take 12 to 18 months.

Under terms of the deal, each former share of Post common stock has been converted into 0.71 of a newly issued share of MAA common stock. Former Post common shareholders hold approximately 32.3 percent of the combined company's common equity, with continuing MAA common shareholders holding approximately 67.7 percent.

Shares of Post common stock and preferred stock will no longer traded on the NYSE.

MAA owned 79,170 apartment units in the Southeast and Southwest regions of the U.S. as of Sept. 30. The merger takes that to 101,207 apartment units, including communities currently in development.

MAA is planning to move its Memphis headquarters to Gill Properties’ new, $90 million mixed-use development called TraVure in Germantown, not far from its existing HQ, both located in the Polar Avenue Corridor. MAA is planning to occupy 80,000 square feet in TraVure’s new Class A office building that is beginning construction. MAA has received a 15-year payment-in-lieu-of-taxes incentive from the city of Germantown in conjunction with the relocation.

The apartment-only REIT is currently in 43,000 square feet at 6584 Poplar, west of Kirby Parkway.

MAA has 1,950 full-time employees, according to Yahoo! Finance, while Post Properties is listed as having 619. It was not immediately clear Thursday how many Post executives might move from Atlanta to Memphis now that the merger is final.