U.S. oil producer Diamondback Energy Inc. on Monday agreed to buy two rivals for a combined $3.2 billion including debt, continuing a consolidation spurred by the coronavirus pandemic-induced oil downturn.

Facing heavy debt burdens and weak oil prices, shale oil producers have been selling at low- to no premiums to market value. Investors, unlike during the 2016 oil slump, have not shown a willingness to put new money into struggling firms.

"It is a realization among small producers how difficult it is to deliver on returns expectations," said Enverus M&A analyst Andrew Dittmar. Sellers are having to accept low or no premium deals with a payoff down the road if the buyer's stock appreciates, he said.

Diamondback will buy QEP Resources in a stock-and-debt that swaps 0.05 of a Diamondback share for each QEP share, or about $2.29, a discount to Friday close. Including debt, the deal is valued at $2.2 billion.

It also agreed to purchase lease interests and assets from Blackstone Group-backed Guidon Operating LLC for 10.63 million shares and $375 million in cash, or about $850 million.

QEP shares lost 8% shortly after midday while Diamondback's shares fell 6% to $43.03.

"Every time Diamondback concludes a transaction it's objectively shown shareholders are better off," Diamondback Chief Executive Travis Stice said. "These are extraordinary times and it creates extraordinary opportunities," he said.

The deals will add to its projected 2021 free cash flow per share and deliver annual savings of $60 million to $80 million after closing by the second quarter of 2021.

The two purchases will add 276,000 acres in West Texas, and increase Diamondback's output by up to 95,000 barrels per day. The QEP deal includes North Dakota properties that the company expects to divest.

Recent deals in the Permian Basin include Pioneer Natural Resource Co's $4.5 billion buyout of Parsley Energy Inc and ConocoPhillips' $9.7 billion deal for Concho Resources Inc.