G.E. Real Estate and Trizec Properties Inc. announced Tuesday that both companies have closed a $5 billion deal to buy Arden Realty Inc.

The General Electric Co. subsidiary is shelling out $4.8 billion, including the assumption of $1.6 billion in debt, for Arden Realty, the largest publicly traded owner of Southern California office buildings.

In connection to the deal, Trizec is paying $1.6 billion for 13 Arden buildings comprising 4 million square feet, including 5670 Wilshire Blvd. and the Howard Hughes Center.

Arden’s remaining buildings will be privately held by G.E. and continue to be operated as Arden Realty. Joaquin de Monet, managing director at G.E. Real Estate, has been named president and chief executive of Arden Realty.

“We invest where there are excellent opportunities for growth, both in asset value and portfolio size,” Joe Parsons, president of North American Equity at GE Real Estate said in a statement. “This transaction significantly expands our footprint in a market that we think is one of the strongest markets in the U.S.”

G.E is filling Arden’s other top executive posts with company veterans.

Robert Peddicord, formerly executive vice president of leasing and operations, is assuming the role of chief operating officer and Andres Gavinet, formerly chief accounting officer, is becoming the company’s chief financial officer.

Howard Stern and David Swartz will respectively remain on as chief investment officer and general counsel.

Through Arden, GE plans to expand the company’s Southern California holdings. GE also plans to add properties in other California markets and in Washington and Arizona to Arden’s portfolio.

As for Trizec, the Arden deal nearly doubles the Chicago-based real estate firm’s Southern California portfolio to more than 8.5 million square feet. Southern California is now Trizec’s largest market, representing approximately 30 percent of the company’s total net operating income.

“We have acquired a large, high-quality portfolio that is well-located in markets that we believe have strong economies, positive employment trends and growing rental rates,” Tim Callahan, Trizec’s president and chief executive officer, said in a statement. “These properties have embedded growth opportunities, and we see significant opportunity to capture value in this portfolio over time.”