Diamondback Energy Inc. announced the pricing of an upsized secondary offer of 12.77 million shares of common stock held by legacy Endeavor Energy stockholders, the Midland, Texas, E&P said on Sept. 19.

Diamondback, which closed its $26 billion merger with Permian Basin E&P Endeavor Energy Resources on Sept. 13, said the gross proceeds from the share’s sale will be approximately $2.2 billion.

Diamondback said it would not receive any of the proceeds.

The Endeavor stockholders have granted underwriters a 30-day option to purchase up to an additional 1,615,500 shares of common stock.

Diamondback has agreed to purchase from the underwriters 2 million shares of common stock that are the subject of the second offering, which is expected to close Sept. 23. The shares will be repurchased as part of Diamondback’s existing buyback program.

Evercore ISI, Citigroup and J.P. Morgan are acting as joint book-running managers for the Secondary Offering.