Shares in Mantra Group tumbled more than 7 per cent on Thursday after Citi downgraded its recommendation for the country's biggest listed hotel and resort operator, amid warnings that the rising Australian dollar could have repercussions for tourism operators.

The Citi Research report, which came out ahead of Mantra releasing its full-year results on August 18, also warned that Airbnb could affect Mantra's ability to lift hotel earnings on the Gold Coast during next year's Commonwealth Games. A further note of concern was lack of major acquisition announcements by Mantra.