Cousins Properties, one of Atlanta’s best known developers and office landlords, has closed its deal to buy rival Parkway Properties of Orlando in an estimated $2 billion merger of real estate investment trusts.

The deal expands Cousins’ reach in its hometown and across the Sun Belt. At the same time, Cousins said it plans to spin off a separate publicly-traded REIT, Parkway Inc., that will own all Cousins and Parkway office properties in the Houston area, which had struggled in recent months.

Houston currently accounts for about 40 percent of Cousins’ portfolio.

Cousins CEO Larry Gellerstedt will continue in his role. He said in an interview last spring, when the deal was announced, that the expanded Cousins will become the top landlord of Class A or top-tier office space in Buckhead, uptown Charlotte and downtown Austin, as well as a major player in Phoenix, Orlando and Tampa.

Cousins will operate about 40 properties nationwide. In Buckhead, Cousins will add trophy towers such as Buckhead Plaza I and II, 3344 Peachtree, Capital City Plaza and the Forum complex.

Atlanta, which has seen office vacancy tighten and rents rise of late to record highs, will make up about half of Cousins’ portfolio after the sale.