Losses in Maybank and Telekom Malaysia led Malaysian shares to a lower finish on Monday as funds stepped up selling on blue chips which have fuelled the index's rise this year.
Analysts said a power failure that hit parts of capital Kuala Lumpur in the morning dampened already cool investor interest.
The 100-stock Kuala Lumpur Composite Index ended 0.70 percent down at 855.76 points, after trading as low as 851.20.
The index has gained about eight percent since the start of 2004, as investors cheer Malaysia's robust economic growth and political stability.
Overall volume was a modest 331 million shares with three losers for every gainer.
"There's no catalyst in the short term. The power failure didn't help," said Melvyn Boey, research chief at J.P. Morgan Malaysia.
A power outage hit some parts of the Kuala Lumpur city centre for an hour from 8.20 am.
A spokesman for national utility Tenaga Nasional said the blackout was due to faulty equipment in one of its sub-stations. Tenaga shares reversed earlier losses to end two percent up at 10.20 ringgit.
Heavyweights Maybank and Telekom Malaysia contributed about half of the index's losses.
Top lender Maybank lost 2.75 percent to 10.60 ringgit while Telekom sank 2.54 percent to 9.60 ringgit.
Among other blue chips which fell, gas distributor Petronas Gas gave up 1.44 percent to 6.85 ringgit. Shipper Malaysia International Shipping Corp lost nearly one percent to 12.70 ringgit. The company said its managing director Mohd Ali Yasin has died of a heart attack.
Shares of national car maker Proton Holdings gained 0.55 percent to 9.20 ringgit after falling seven percent last Friday when it resumed trading after an organisational revamp.
Proton shares were suspended to allow the firm to create a holding company to house different business units and enable them to pursue joint ventures.