HOUSTON (Reuters) – Oil and gas producer Occidental Petroleum Corp on Wednesday made a $57 billion bid for Anadarko Petroleum Corp, topping Chevron Corp’s $50 billion offer and sparking the first takeover battle for a major oil company in years.

The surprise $76-per-share bid comes after Occidental had been trying to woo Anadarko and had made two other proposals since late March. Anadarko plans to reply to the offer later in the day, a spokesman said.

The bid pushed Anadarko shares up more than 11 percent in early morning trading to $71.25, well above the $65 per share offered by Chevron. Occidental shares fell about 2 percent to $61.07.

Occidental, which has made two previous offers, boosted the cash portion to 50 percent. Chevron’s offer comprised 25 percent cash and 75 percent stock.

A deal would boost Occidental’s production in the lucrative Permian to 533,000 barrels of oil equivalent production per day, the company said.

“We are very confident. Our proposal is so strong, it’s definitely superior, and we now know the value which we can communicate to shareholders,” Vicki Hollub, Occidental’s chief executive officer, said in an interview. She said the deal would boost cash flow and allow Occidental to raise its dividend over time.

Still, Occidental has lost 7 percent of its value since it first disclosed its interest in Anadarko.

“We don’t think a bidding war with Chevron (CVX) is in the best interest of OXY shareholders,” analysts at KeyBanc Capital Markets wrote in a client note.

Occidental is “going head-to-head against a supermajor four times its size” and Chevron is likely to emerge as the winner for Anadarko, said Pavel Molchanov of Raymond James. But he added, “this is an extremely fluid situation, and we have to be candid that any predictions are merely guesses at this point.”

A combined Oxy and Anadarko would be a “long term leader in the Permian,” Hollub said, noting that Anadarko’s shale assets in the Permian Basin and Colorado’s Denver Julesberg Basin are most appealing to Oxy.

Anadarko also has significant offshore Gulf of Mexico assets and an LNG project in Mozambique that is expected to go to a final investment decision soon.

“The value of this is in the shale,” Hollub said on a call with analysts.

The offer would require shareholder votes by Occidental and Anadarko shareholders. Anadarko would be liable to pay Chevron a $1 billion break-up fee if its board chooses Occidental’s offer.

“It is unfortunate that Anadarko agreed to pay a break up fee of $1 billion, representing approximately $2 per share, without even picking up the phone to speak to us after we made two proposals during the week of April 8,” Hollub wrote in a letter to Anadarko’s board on Wednesday.

Analysts have said they expect the industry to consolidate more as small oil producers, who revolutionized the sector through advances in horizontal drilling and hydraulic fracking, have had to cut spending as investors press for higher returns and their stock prices languish.

The Permian produces about 4 million barrels per day, and is expected to hit 5.4 million bpd by 2023, according to IHS Markit, more than the total production of any OPEC country other than Saudi Arabia.

Occidental’s $76 per share offer comprises $38 in cash and 0.6094 of its shares. The offer represents a premium of 19 percent to Anadarko’s closing price on Tuesday and 62 percent to the closing price on April 11, the day before Chevron made its bid.

Under Chevron’s $65 per share bid, Anadarko shareholders would receive 0.3869 shares of Chevron and $16.25 in cash for each Anadarko share.