TORONTO -- Air Canada said Thursday it will launch its own loyalty rewards plan in 2020 and not renew its contract with the company running Aeroplan, sending Aimia's stock plummeting by more than 50 per cent.

The Montreal-based airline (TSX:AC) says customers will be able to continue collecting Aeroplan points until June 2020, after which miles earned from flying on Air Canada or its 26 Star Alliance partners will be credited to the in-house loyalty program instead. Travellers will be able to redeem those points for Air Canada and Star Alliance flights.

The airline said it intends to continue allowing Aeroplan members to redeem their Aeroplan points for seats on their flights after June 2020. However, Aimia's CEO said that isn't certain yet, as there are still a lot of discussions to be had.

Aimia (TSX:AC) shares fell 57 per cent to $3.81 in early morning trading.

"This is something we've anticipated," Aimia CEO David Johnston said in an interview on his first day on the job after serving several months on an interim basis. The company announced Wednesday evening that Rupert Duchesne, who has been on medical leave, is retiring from the top role.

Johnston said the company has been planning for this possibility and is exploring a range of alternatives for its business after Air Canada's contract ends, including pursuing other partners.

He assured the program's five million customers they can expect a smooth transition.

"There's three years left to run on the contract and in that period, it's business as usual," Johnston said.

Air Canada said in a statement it's aiming to strengthen its relationships with customers in making the switch. The airline did not immediately respond to a request for comment. Air Canada's stock rose more than 7 per cent $15.99.

Aeroplan was originally Air Canada's in-house loyalty program. It was spun off as an independent business, now called Aimia Inc., which has expanded its customer base and evolved its services over the years.

The company has 5 million active members, who have a total of about 200 billion miles on their balances.