At 12.30pm, the key index was up 4.17 points to 1,559.88.
"The unabated spread of Covid-19 in the country, which may lead to further pressure on the economy, coupled with the concerns over the revised nation's growth projection by the World Bank have sent the FBM KLCI lower.
"Following a heavy selldown, we might anticipate bargain-hunting actiities to emerge on the local bourse," said Malacca Securities Research in its daily outlook.
It noted that the index has broken below the immediate support level of 1,565. It set resistance at 1,580 while the next support level is around 1,550.
Leading the rebound were Petronas Chemicals up seven sen to RM8.07, Press Metal rising 11 sen to RM4.82 and MISC gaining six sne to RM6.82.
Financial heavyweights on the rise included Hong Leong Bank up 10 sen to RM18.90, Public Bank gaining one sen to RM4.19 and CIMB rising two sen to RM4.72.
Hartalega continued its slide, falling 13 sen to RM7.54, and Top Glove rose one sen to RM4.36.
Top actives on the broader market were MMAG down two sen to 14.5 sen, Serba Dinamik dropping five sen to 48.5 sen and Focus up 0.5 sen ot 4.5 sen.
In Asian markets, equities tracked Wall Street higher after US President Joe Biden secureed a bipartisan Senate infrastructure deal, which will further boost economic recovery.
Japan's Nikkei rose 0.8% and South Korea's Kospi gained 0.6%. In China, the composite index gained 0.7% while Hong Kong's Hang Seng scaled 1.1%. Australia's ASX200 added 0.3%.