Southwest Airlines orders 40 Boeing 737 MAX jets worth $4.68 billion

Southwest Airlines is making a move to modernize its fleet.

The low-cost carrier says it has ordered 40 Boeing 737 MAX 8 jets worth $4.68 billion at list prices.

10 planes will be delivered each year from 2019-2022, Southwest said in a statement.

"This is first and foremost an extension of our fleet modernisation strategy," Southwest chief executive officer Gary Kelly told analysts on a post-earnings conference call, according to a transcript.

Southwest is the world's largest operator of 737 jets, with more than 700 of the airplanes.

The airline on Thursday warned of the consequences of the mid-air engine explosion on a 737-700 last week.

As a result of the accident, Southwest expects softer bookings and thus a decline in revenue per seat mile (RASM) in the range of 1% to 3% in the second quarter of the year.

Southwest reported first-quarter earnings before the opening bell on Thursday. The company posted earnings per share of 75 cents, narrowly beating Wall Street’s estimate of 74 cents. While its revenue of $4.9 billion for the quarter missed analysts’ predictions of $5.01 billion, it was still a 1.9% increase from the same period in the prior year.

FOX Business’ Matthew Kazin contributed to this article.