Shares of Air Canada fell on Friday after a U.S.-based analyst cut her rating on the company’s stock, citing potential headwinds that could hold back the airline’s performance.

Cowen analyst Helane Becker downgraded Air Canada to Market Perform from Outperform, while maintaining her price target at $51 per share.

In her report, Becker told clients Air Canada is a “victim of their own success”, considering the company’s stock rose about 87 per cent last year. She added that at current prices there are limited catalysts to move the shares higher.

As well, Becker cited “potential headwinds” that could hold back Air Canada’s short-term performance, including risks tied to the pending takeover of Transat AT. Indeed, Becker described Transat’s financial track record as “spotty”, leading to concern it “may take time” for Air Canada to make the brand sustainably profitable, which could cause earnings dilution in the first year following closing.

The second headwind cited in the report is the international expansion of rival Westjet, which is now under private ownership after agreeing to a takeover by Onex Corporation which, accordingly to Becker, could allow the Calgary-based airline to become “more aggressive” in the international and domestic markets.  

The report also mentioned uncertainties surrounding the return to service of the Boeing 737 MAX. The plane is being reviewed by international regulators following two fatal crashes last year. While Air Canada and Westjet are MAX operators, Becker said she expects Air Canada to be “disciplined” with the eventual re-entry of the MAX to active service, while Westjet might be more aggressive, considering the company’s reliance on the aircraft.