There’s turbulence ahead for Copa Holdings as Mexico’s Volaris plans to grow in Central America.

At least that’s the opinion of Victor Mizusaki at Bradesco BBI. The analyst has had an underperform recommendation on Copa since May 2016—the stock is up more than 100 percent since then. Mizusaki’s sticking to his guns even after Copa reported fourth-quarter results that beat estimates on Feb. 21. Shares are up 4.4 percent in New York since the earnings report.

“We continue to be concerned about competition from ultra-low-cost airlines,” Mizusaki wrote in a note. “Volaris Costa Rica, for example, announced on February 19 four routes from El Salvador, Costa Rica and Guatemala, to Los Angeles, New York and Washington. We believe that the expansion of low-cost airlines in the region will generate competitive pressures for COPA and could put the company’s guidance at risk.”

Central America accounts for 23 percent of Copa’s revenues, according to Bradesco. Mizusaki also questions Copa’s guidance for an Ebit margin between 17 percent and 19 percent, saying the airline assumes a healthier competitive landscape than is true.

UBS analyst Rogerio Martins also has a sell on Copa, with the market pricing in unrealistic Ebit margins above guidance. He upgraded Volaris to buy on upside potential from yield recovery this year.

Mizusaki and Martins, who’s rated Copa at sell since March 2016, are the only ones bearish on the stock. Nine others have buy or hold recommendations, according to data compiled by Bloomberg. That’s more positive ratings than any of its regional peers.