At 12.30pm, the country's key index was down 14.39 points to 1,534.12. Market breadth was overwhelmingly negative with 883 decliners versus 172 gainers.
Investors were in a selling mood amid an absence of positive catalysts while national holidays in Japan, China and South Korea added to the dearth of trading direction.
Press Metal remained a leading drag on the FBM KLCI, shedding 15 sen to RM5.65 while Top Glove fell 17 sen to RM2.89 following analyst downgrades to its earnings outlook.
Sime Darby Plantation lost 11 sen to RM3.69, Petronas Gas slipped 52 sen to RM16.86 and Tenaga Nasional fell 10 sen to RM9.80.
Meanwhile, IGB Commercial REIT, which made its debut on the Main Market of Bursa Malaysia, hit limit down after plunging 30 sen or 30% to 70 sen with nearly 15 million shares done.
Most active stocks were Emico down one sen to 65.5 sen, DNeX sliding 3.5 sen to 76.5 sen and Pasukhas falling one sne to 10.5 sen.
While most major Asian marets stayed shuttered for the mid-Autumn festival holiday, Hong Kong's maret fell deep into the red with the benchmark Hang Seng plunging nearly 4% on the back of a rout in China Evergrande's share price.
The debt-riddled developer dropped 19% to a low of HK$2.06 in Monday trade on fears that its collapse from a debt of US$300bil would have far-reaching implications for China's financial system.
Australia's ASX200 meanwhile was down 2.25%.