Republic Airways Holdings Inc said on Tuesday it would sell Frontier Airlines to private equity firm Indigo Partners LLC in a deal valued at about $145 million.

The agreement ends a two-year-long search by Indianapolis-based Republic to unload Frontier, which it bought out of bankruptcy in 2009.

Phoenix-based Indigo will pay $36 million in cash for the equity of Frontier Holdings and assume Frontier’s debt.

Republic, which provides regional service for bigger carriers such as Delta Air Lines Inc and United Continental Holdings Inc, has been restructuring Frontier over the past year to lower its costs.

Indigo is led by co-founder William Franke, who was chairman of low-cost carrier Spirit Airlines Inc.

“We endorse and will support continued efforts to build Frontier into a leading nationwide ultra-low cost carrier,” Franke said in a statement. “As airline fares continue to move up, passengers need affordable travel alternatives.”

The deal is subject to various approvals and is expected to close in December, Republic said.

Shares of Republic closed at $11.89 on the Nasdaq on Monday.

Photo Credit: Frontier has been sold and it is poised to be the next super-low-cost carrier. Pictured is a Frontier Airbus A319-111 in 2011. Flickr