Delta is on an airplane shopping spree with 2 billion dollar deals in 2 days

Delta Air Lines has place an order for 37 Airbus A321ceo airliners.

This comes one day after the Atlanta-based airline announced the purchase of 75 Bombardier CS100 airliners.

At list prices, the 37 jets have a total value of $4.25 billion.

However, with Airbus looking to fill out its production slots before the next generation A321neo arrives, Delta is likely to have negotiated a very substantial discount to the tune more than 50% off list price.

This is the third substantial order Delta has placed with Airbus in recent years, and the second for the A321ceo.

"The order for the A321s is an opportunistic fleet move that enables us to produce strong returns and cost-effectively accelerate the retirement of Delta's 116 MD-88s in a capital efficient manner," Delta's incoming CEO Ed Bastian said in a statement.

The A321s from this order will also likely be deployed as a more fuel-efficient alternative to Delta's fleet of almost 120 aging Boeing 757-200 jets.

The Atlanta-based airline currently boasts a fleet of 809 mainline jets from Airbus, Boeing, and McDonnell Douglas with an average age of 17.1 years.

Delta looks to be keen to bring its fleet age in-line with its fellow legacy carriers American - which is at 11.2 years of age - and United - at 13.6 years.

In 2013, Delta ordered 30 A321s along with 10 A330-300 wide-body jets from Airbus. The first A321 from that order is expected to enter service next week.

In late 2014, Delta returned to Airbus for a batch of 50 wide-body A350-900XWB and A330-900neos with a list value of more than $14 billion.

In recent years, Delta is earned a reputation for being highly effective at searching out and taking advantage of undervalued assets. In the mid-2000s, as others dumped their fleets of McDonnell Douglas MD-80/90 jets in favor of newer, more fuel efficient models, Delta picked them up second-hand for pennies on the dollar.

Delta's deal to become the Bombardier C-Series' US launch customer also came with a substantial discount. Although the deal has a list price of $5.6 billion, an industry source told Business Insider that the Delta received a 65% to 70% discount.

The 37 A321s in the order is expect to be delivered by 2019.