The composite SET index declined by 26.04 points or 1.98 per cent, to 1,288.59 points. Turnover was as low as Bt27.6 billion.
Investors were spooked by the violence on the advance voting date on Sunday. Meanwhile, it is uncertain whether the election would take place on February 2 as scheduled.
"If the government is adamant that the election would take place on February 2, the SET index could fall under heavier pressure," Asia Plus Securities said in a research note.
Convening on January 28, the US Federal Reserve is expected to further cut the bond-buying programme by another US$10 billion a month in February thanks to improvement in some economic indicators. The monthly purchase will be only $65 billion. Unemployment rate has fallen to 6.7 per cent.
Meanwhile, the Turkish lira hit another record low value against the dollar on Monday despite heavy central bank intervention in the foreign exchange market last week. The lira tumbled to 2.3616 to the dollar and 3.2345 to the euro in morning trading, after touching 2.33 and 3.20 on Friday. The fall of the lira is rooted in an escalating political crisis over the corruptiuon scandal that ensnared key allies of Prime Minister Recep Tayyip Erdogan, as well as concerns about the economy. The central bank has been under strong political pressure not to raise interest rates.
On Friday, Argentina's peso saw its sharpest one-day fall since the country's 2002 financial crisis. The peso fell 11 per cent to stand at an official rate of eight pesos to the dollar. Investors have lost confidence in the country. Despite efforts to support the economy, inflation has soared to 25 per cent.