Southern Company, among the largest U.S. electric and natural gas distribution companies, said Thursday it had signed a deal to sell Sequent Energy Management, its wholesale gas trading and services business, in a move to reduce risk.

The Atlanta-based firm disclosed the planned sale, expected to close in the third quarter, along with its first quarter earnings results.

During a call with analysts and investors, executives said the sale was signed at book value so Southern would not see material gains or losses. However, executives said, it will enable the company to shed a volatile piece of its earnings per share (EPS) and free up capital.  

“It will provide a return of the associated working capital and the elimination of certain credit supports of approximately $1...