Shares in UK carrier Flybe dropped 37 percent on the London Stock Exchange after Europe's largest regional airline said there was a significant slowdown in sales across its UK domestic network in September.
The company, which along with Finnair recently bought Finland's biggest domestic carrier Finnish Commuter Airlines, also said total revenue for the first-half was about 1 percent behind its expectations.
"This is clearly disappointing after a strong first-quarter and progress made with the Finncomm acquisition," Investec analyst Andrew Fitchie said in a note.
"If September trends were to continue, second-half revenues would be 5-7 percent below our expectations," he said.
"We still see long term value in the Flybe shares, but given the likely disappointment over downgrades and the uncertainty over the trading outlook, it is difficult to see the shares performing short term," Fitchie added.