The Constitutional Court has ruled against PM Yingluck Shinawatra and nine of her cabinet members, and appointed Niwattumrong Boonsongpaisan as caretaker Prime Minister.
At issue was whether she abused her power by transferring the national security chief in 2011 apparently for the benefit of her Pheu Thai Party. Ms Yingluck denied allegations and stated she didn't receive any benefit from the appointment.
There are several other cases pending against Ms. Yingluck as well.
Thai stocks have been mostly ignoring the political troubles over the past few weeks and were little-changed overnight.