Developer Portman Holdings announced this week it has formally started construction on the company’s third office tower at Midtown Atlanta’s Technology Square.

Health insurance giant Anthem will anchor the new tower at 712 West Peachtree Street, which is expected to open in 2021. The 20-story tower will rise at 4th and West Peachtree streets next to Portman's two other Midtown towers known as 740 West Peachtree and Coda.

Midtown and the Tech Square area have witnessed a rush in new office leasing and development as major corporations seek a foothold on Georgia Tech’s doorstep. NCR relocated its headquarters to a new two-tower complex in Midtown from Gwinnett County, and companies including Panasonic, Keysight Technologies and Equifax have announced large Midtown expansions in recent years.

Norfolk Southern and developer Cousins Properties recently launched construction on the railroad giant's new headquarters along West Peachtree Street just south of the Portman buildings.

For Anthem, the parent company of Blue Cross/Blue Shield, this will be the second tower it will lease from Portman at Tech Square. In October 2017, Anthem said it would move the technology center it announced in Midtown a year earlier to 740 West Peachtree Street.

At 740 West Peachtree, Anthem said it will have room for 3,000 information technology and software development professionals.

In a statement, Anthem said it will consolidate its Buckhead and downtown operations into the new 712 West Peachtree building.

“We have announced some future changes to our Atlanta-area office locations that will enable us to provide improved worked environments for our employees and enhance our strong collaborative culture, as we focus on creating a better health care experience for the communities and customers we serve,” the company said in a statement.

Anthem’s plans to occupy the second tower were first reported by Atlanta Business Chronicle.

Tenants, including Georgia Tech, recently started moving into the Coda tower, which will hold its formal opening in the coming weeks. The 740 West Peachtree tower is expected to open in 2020 and its sibling at 712 is scheduled to open the following year.

“We are pleased to commence the construction of a third office tower on West Peachtree, adjacent to the Anthem Technology Center and Coda Tech Square,” Ambrish Baisiwala, Portman Holdings CEO, said in a news release. “712 West Peachtree continues a legacy of creating vibrant and innovative work spaces and our continued investment in Midtown Atlanta.”

The three Portman Holdings towers are designed by John Portman & Associates, the architectural arm of the empire founded by late legendary Atlanta architect and developer John C. Portman Jr.

Anthem will occupy about 85 percent of 712 West Peachtree and the entirety of 740 West Peachtree. The two towers will share lobby space and an eighth-floor outdoor terrace, the news release said.