Shares in AirAsia fell 7.8 percent on Monday, their biggest one-day drop in more than three years after one of its aircraft went missing on its way to Singapore from the Indonesian city of Surabaya.

Analysts said the Sunday incident involving AirAsia's Indonesia unit may cause some travelers to be wary about flying with the AirAsia group, affecting its prospects to improve yields and bolster its profit in the year ahead.

"I was expecting yields to at least maintain on a year-on-year basis in 2015, but now I'm expecting them to decline by up to five percent," said Daniel Wong, an analyst at Kuala Lumpur-based Hong Leong Investment Bank.

The research house downgraded AirAsia from a "buy" to a "trading sell" on Monday morning.

The Kuala Lumpur-traded shares of AirAsia had fallen 7.8 percent as of 0320 GMT, their biggest daily drop since Sept. 22, 2011. The stock had dropped as much as 12.9 percent after the opening, compared with a 0.4 percent decline in Kuala Lumpur's benchmark index.

Despite the decline, the stock has gained more than 20 percent since the beginning of the year, compared with the index's 5 percent fall.

About 59.5 million AirAsia shares had been traded, making it the bourse's most active stock. That was about 5.2 times the stock's average full-day volume over the past 30 days.

The Bangkok-listed shares of Asia Aviation, the holding company for Thai AirAsia in which the AirAsia group holds a 45 percent stake, fell 3.6 percent on Monday.

Indonesia AirAsia is 49 percent owned by Malaysia-based budget carrier AirAsia, with local investors holding the rest. The AirAsia group, including affiliates in Thailand, the Philippines and India, has not had a crash since its Malaysian operations began in 2002.

Indonesia resumed its search for the missing jetliner QZ8501 at first light on Monday.

Hafriz Hezry, an analyst with AmResearch, expected the stock to recover within a few days after the market's initial reaction to news of the missing airplane.

AirAsia's reputation at the group level may take a hit, affecting its yield recovery next year, he said, but the impact on AirAsia's earnings would be minimal because its share of theIndonesia unit's profit will not be included in its earnings until the unit has reversed unrecognized losses, which could take several quarters.