Indigo Partners, the private equity firm managed by veteran US low-cost airline investor Bill Franke, is selling its 18.7% stake in eastern European budget carrier Wizz Air for £249 million.

Phoenix-based Indigo Partners, whose investments have also included Mexico’s Volaris, Frontier Airlines, Spirit Airlines and Tiger Airways, first invested in Hungary-based Wizz Air in 2004.

Wizz floated shares on the stock market in February 2015 at an initial offer price of 1,150 pence.

Indigo sold 10.7 million shares at a price of 2,320 pence per share.

It also holds 44.8 million convertible shares and convertible notes, which if fully converted would entitle the firm to an additional 24.2 million new ordinary shares, Indigo Partners said.

Wizz Air’s market capitalisation stands at £1.37 billion.

Franke made his name as a champion of unbundled fares in ultra-low cost airlines, where passengers are offered cheap base ticket prices with extra charges for other services.