The Istanbul-based budget carrier placed a firm order for 58 fuel-saving A320neo aircraft and 17 A321neo jets. The aircraft have a combined list price of $7.5 billion.

The deal also includes options for a further 25 aircraft. If all options are exercised, the deal's value for all 100 aircraft could rise to $9.9 billion, based on official Airbus prices. In practice, airlines win significant discounts for large orders.

Pegasus currently operates aircraft built by Airbus's arch-rival Boeing (BA.N). It switched allegiance after what industry sources described as a tough price contest between the planemakers, during negotiations first reported by Reuters.

The competition is the latest milestone in what has, over the past year, become the fiercest worldwide contest for market share between Airbus and Boeing in a decade.

Founded in 1990, Pegasus has grown its fleet from just two aircraft to more than 40 mostly Boeing BA.N 737-800s over the past two decades and serves 52 destinations in 24 countries.

Its latest expansion highlights rapid growth in Turkish aviation after flag carrier Turkish Airlines (THYAO.IS) recently ordered long-range aircraft from both Boeing and Airbus.

(Reporting by Evrim Ergin in Istanbul and Tim Hepher in Paris; Editing by Nick Tattersall)

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