Tech giants and other major listed firms posted weaker-than-expected earnings in the second quarter, dampening investor sentiment amid a capital outflow ahead of a looming U.S. interest hike, data showed Tuesday.

Half of 38 companies with market capitalization over 1 trillion won (US$856.16 million) chalked up April-June earnings that missed market estimates as of Friday, the corporate researcher WISEfn said.

Samsung Electronics Co., the world's largest handset maker, logged 6.96 trillion won in operating profit, slightly below the market consensus. Chip giant SK hynix's 1.37 trillion won operating profit also fell shy of the median market forecast.

Samsung Engineering Co., an engineering subsidiary of Samsung Group, logged 14.9 billion won of operating income, less than half of the guidance.

OCI Ltd., a solar power company, registered 6.2 billion won in operating profits, falling 85.5 percent of the market consensus at 42.8 billion won provided by local brokerage houses.

Their lackluster performances sparked worries over the equity market as foreigners have turned net sellers because rising expectations for U.S. rate hikes have sapped appetite for riskier assets.

"Investors remain highly cautious as concerns over the second-quarter earnings became reality," Kim Jin-young, a researcher at NH Investment & Securities, said. "It would take considerable time to recover the investor sentiment for large-caps sensitive to economic cycles as exporters are lagging far behind."

   Adding to the concerns are major shipbuilders, which are poised to announce dismal earnings later this week due to the delivery of low-priced ships and a delay in the construction of loss-making offshore facilities.

Daewoo Shipbuilding, the world's No. 2 shipyard, is projected to book massive losses, around at least 1 trillion won, on its balance sheet for the second quarter.

Samsung Heavy Industries also may report an operating loss of up to 1 trillion won during the April-June period, as the country's No. 3 shipbuilder considers reflecting the accumulated loss from its offshore facilities deals into its second quarter performance.