Ryanair said it plans to buy at least 150 Boeing 737 Max 10 planes with options for 150 more, after a price dispute derailed negotiations for the large order in 2021.

It’s the budget carrier’s biggest order and the manufacturer’s latest sizable deal for new planes as airlines replace aging jets and grow their fleets.

Shares of Boeing were up close to 2% in afternoon trading Tuesday after the company reported the order, while the broader market was down.

Ryanair plans to operate the Max 10s, which haven’t yet been certified by regulators, with 228 seats on board.

The 150 planes in the firm order are worth more than $20 billion at list prices, but airlines generally receive significant discounts for such big sales. Ryanair stopped negotiations for a big Max order in September 2021 over the pricing dispute.

“In our view it will never be cheap enough and in Boeing’s view it’s always far too cheap,” Ryanair CEO Michael O’Leary said at a press conference.

The planes will replace older 737 jets in Ryanair’s fleet. The aircraft will likely be delivered between 2027 and 2033, O’Leary said. The 150 additional jets it has optioned would allow it to fly more than 300 million passengers a year by 2034 and would create 10,000 jobs by then, he said.

The ultra-low-cost airline flew 97 million passengers in the 12 months ended March 31, down from 149 million before the Covid pandemic, according to a company report.

The budget carrier’s order is the latest in a string of big sales for Boeing, which has reached agreements to sell hundreds of planes to customers including Air India, Saudia and United Airlines in recent months.

Boeing’s next challenge is ramping up production of the 737 Max. Last month the company said it aims to make 38 each month, up from 31. The company plans to open a fourth production line for the best-selling plane and increase rates to 50 a month in 2026.

Supply chain struggles as the Covid-19 pandemic eased have hamstrung both Boeing and Airbus production goals.

Boeing CEO Dave Calhoun said at the joint press conference Tuesday that current customer demand would support rates “significantly higher” than what the company has planned, but supply chain issues are preventing further expansion. Delivery delays have vexed airline executives who are trying to capitalize on the travel rebound.

Boeing said Tuesday that it delivered 26 aircraft last month, down from 64 a month earlier. Eighteen of those deliveries were 737 planes. The company had warned that a production flaw on some 737 Max jets would delay deliveries on certain models.

When asked whether Boeing would consider a fifth production line, Calhoun said: “We will be evaluating every step of the way whether we need more capacity or not.

“If the supply constraints that we experience today … relax somewhat, that day could come, and nothing would make us happier,” Calhoun said.

He said the company expects the 737 Max 10 to be certified in 2024.

“We won’t give you a date because that’s not our job, it’ll be the FAA’s,” he said.

O’Leary said he has “no fear” that the high-density aircraft configuration will win regulators’ approval.

The budget airline’s model attracts travelers with low fares and then add-on fees for everything from seat assignments to checked bags. O’Leary said there is “no truth to the desperate and dastardly rumor” that the carrier will charge passengers to use bathrooms on board.