Kenanga research said the index's technical outlook remained bearish despite the 3.28% week-on-week gain as the primary downtrend remained intact with the share trading below its 100-day simple moving average.
"Should the index break above its 100-day SMA, we opine outlook should turn bullish.
"From here, resistance levels can be identified at 1,670 (R1) and 1,705 (R2). Conversely, supports can be found at 1,610 (S1) and 1,585 (S2)," it said.
At 12.30pm, the FBM KLCI was down 4.58 points to 1,646.18, weighed down mainly by falls in Axiata and Digi.
Trading was muted in the lead-up to the Hari Raya celebrations, with volume coming to 94.58 million shares valued at RM614.47mil.
There were 531 declining counters versus 163 advancers and 310 unchanged.
Under the spotlight for their merger plans, Axiata slipped 12 sen to Rm4.57 while Digi dropped 11 sen to RM4.86.
Petronas Gas was another leading decliner, sliding 22 sen to RM17.44 while Maybank dipped two sen to RM9 and Public Bank shaved four sen to RM23.56.
Eking out small gains were Maxis adding one sen to RM5.55 and IHH rising one sen to RM5.51.
Stocks seeing the most investor interest in the morning were Hibiscus slumping 4.5 sen to 99.5 sen, Lambo dropping 0.5 sen to 5.5 sen and Bumi Armada unchanged at 20 sen.
The combined pressure of rising US-China trade tensions and Washington's new tariff threats on Mexico continued ramped up the selling pressure in equity markets.
The Shanghai Composite Index fell 0.5%, the CSI300 Index dropped 0.2% and Hong Kong's Hang Seng Index slid 0.35%. Japan's Nikkei Index plunged 1.26% while South Korea's Kospi Index bucked the trend, rising 1%.
The rout in oil markets continued after having fallen over 3% on Friday as the trade tensions weighed on the demand outlook.
US crude fell 60 cents to US$52.90 a barrel and Brent crude dropped 88 cents to US$67.11 a barrel.
In currencies, the ringgit rose 0.25% against the US dollar to 4.1797. It was unchanged against the pound sterling at 5.2834 and down 0.25% against the Singapore dollar at 3.0490.