Memphis-based Mid-America Apartment Communities Inc. (NYSE: MAA) announced it is buying Atlanta-based Post Properties Inc. (NYSE: PPS) to form the largest publicly traded multifamily apartment real estate investment trust by units.

The combination, which values Post at just under $4 billion, will result in a Sunbelt-focused, publicly traded, multifamily REIT with a total market capitalization of approximately $17 billion.

Under terms of the agreement, PPS shareholders will receive 0.71 shares of newly issued MAA common stock. Following the merger, MAA equity holders will hold approximately 67.7% of the combined company’s equity, and former Post equity holders will hold approximately 32.3% on a pro forma basis. The all-stock merger is intended to qualify as a tax-deferred transaction. Following the approval of a majority of both the MAA and Post shareholders, the transaction is expected to close during the fourth quarter of 2016.

MAA currently owns or has ownership interest in 80,846 apartment units in 15 states, while Post Properties has 24,162 apartment units in 61 communities in Georgia, Texas, Florida, North Carolina, Maryland, Virginia and Washington, DC.

Following the merger, the REIT will own approximately 105,008 multifamily units in 317 properties focused largely in Sunbelt region of the US. Its 10 largest markets by unit count will be Atlanta, Dallas, Austin, Charlotte, Raleigh, Orlando, Tampa, Fort Worth, Houston and Washington, DC.

“The combined company will capture a broader market and submarket footprint, with improved rental price-point diversification that will support an enhanced level of performance over the full real estate cycle,” said H. Eric Bolton, Jr., MAA Chairman and CEO, in a statement announcing the merger agreement. “The Post development platform, with a strong history of value accretive new development, supported by the newly combined company platform, will expand external growth and accretive capital recycling opportunities for MAA.”

Both MAA’s and Post’s boards have unanimously approved the merger. The number of directors on MAA’s board will increase to 13, with three directors designated by Post from its existing board. In addition, Bolton will serve as CEO and chairman of the Board of Directors of the combined company.

Following the merger, the company will keep the Mid-America Apartment Communities’ name and trade under its MAA ticker symbol. The combined company’s corporate headquarters will be located in MAA’s offices in Memphis. The REIT plans to maintain major offices in Atlanta and Dallas, including management and resources supporting new development operations.