Athlon Energy Inc. (NYSE: ATHL) opened a public offering of 12.5 million common shares, the company said July 30, noting that the selling stockholders were funds associated with Apollo Global Management LLC (NYSE: APO).

The selling stockholders granted the underwriters a monthlong option to purchase up to 1.9 million additional shares, Athlon added. Athlon will not sell any shares or receive any proceeds, the company noted.

Citigroup Global Markets Inc. and Goldman, Sachs & Co. (NYSE: GS) are joint book-running managers, the company said. Fort Worth, Texas-based Athlon Energy Inc. acquires and develops Permian Basin oil and natural gas.