MAS, which counts state investor Khazanah as one of its major shareholders, is Malaysia's second largest airline by market value, trailing only budget carrier AirAsia.
The Boeing 777, carrying 239 people, disappeared on Saturday from radar, less than one hour after leaving Kuala Lumpur for Beijing, China.
Officials investigating the disappearance of the airliner are narrowing the focus of their inquiries on the possibility that it disintegrated mid-flight, a senior source said on Sunday.
More than 48 hours after contact was lost there was still no sign of the aircraft and no wreckage had been found.
A Vietnamese navy plane spotted an object suspected of belonging to the airliners late Sunday, but it was too dark to be certain the object is part of plane. More aircraft will be dispatched to the area on Monday morning.
Malaysia Airports Holdings, the operator of Kuala Lumpur International Airport where the Boeing 777 last took off, saw its shares fell 2.39% to 8.18 ringgit a share.
Shares of AirAsia dropped 1.19% to 2.49 ringgit per share at 01:04 GMT, while long haul budget airline suffered 0.62% drop to 80 sen.
Malaysia's benchmark index declined 0.61%.