April 29 (Reuters) - Oil and gas firm Diamondback Energy ( FANG )

said on Monday it had received a second request from

the U.S. Federal Trade Commission (FTC) in connection with the

$26 billion deal to buy privately-held Endeavor.

The U.S. antitrust regulator has asked for additional

information and documentary material as part of its review of

the proposed merger.

CONTEXT

Midland, Texas-based Diamondback had said in February it

would buy privately held rival Endeavor Energy Partners in a

cash-and-stock deal, which is expected to close in the fourth

quarter.

The combined company would be the third-largest oil and gas

producer in the Permian Basin of West Texas and New Mexico,

behind Exxon Mobil ( XOM ) and Chevron ( CVX ).

U.S. lawmakers have sought increased scrutiny of

multi-billion dollar deals in the oil and gas industry from the

FTC.

WHY IT IS IMPORTANT

This is the fifth oil and gas deal since December to get a

second request from the FTC. Other deals to receive second

notices include the Exxon - Pioneer, Chevron ( CVX )

- Hess and Occidental - Crownrock

.

Earlier this month, Chesapeake Energy ( CHK ) and

Southwestern Energy ( SWN ) said the closing date of their

proposed $7.4 billion merger had been pushed back to the second

half of the year after receiving a second request for

information from the FTC.

BY THE NUMBERS

The combined Diamondback-Endeavor company would pump

816,000 barrels of oil and gas per day (boepd), behind the

Exxon-Pioneer combination of about 1.3 million boepd and

Chevron's ( CVX ) 867,000 boepd in the basin.