HONG KONG (MarketWatch) -- Asian markets were dealt crushing blows Friday as panic-stricken investors rushed to dump stocks across the board in a scramble to raise cash and reduce risk.

Japanese shares were hurt the most in the resulting stampede, with the Nikkei 225 Average delivering its worst single-day performance in more than two decades.

The benchmark took home a weekly loss of 24%, while more than $650 billion of wealth was wiped off during this period in Tokyo - Asia's largest stock market by capitalization - according to FactSet Research data.

At their lowest levels during the session, the Nikkei tumbled as much as 11.4% in Tokyo, the Hang Seng Index lost 9.7% in Hong Kong, the Kospi index shed 9% in Seoul and India's Sensex slumped 9.6%, although they ended modestly above than the day's lows.

"We have a complete market disarray, where valuations aren't even appropriate to mention," said Benjamin Collett, head of hedge-fund sales trading at Daiwa Securities SMBC.

"We've had a cascading series of events which have served to force equity holders to offload shares under a massive amount of distress," he said. "That means that they are selling at 15 to 30 cents on the dollar and there is no risk appetite or funding to allow someone to catch this drop."

The Nikkei ended the day 9.6% down at 8,276.43, its lowest close since May 2003. The day's percentage loss was the worst for the benchmark since the 1987 market crash, according to Reuters. The broader Topix index fell 7.1% to 840.86.

The Hang Seng Index tumbled 7.2% to 14,796.87, while the Hang Seng China Enterprises Index slumped 7.9% to 7,135.80.

China's Shanghai Composite ended 3.6% lower at 2,000.57 and the Straits Times Index fell 7.6% to 1,942.50 by late afternoon.

In Mumbai, the Sensex fell as low as 10,239.76 in early minutes of trading, before paring some losses. The index was down 5% at 10,766.04 in afternoon trading. The drop came even after the central bank further reduced banks' cash reserve requirement. The central bank cut the requirement by 1.5 percentage points, from 0.5 point planned earlier. The move, designed to inject liquidity into the banking system, sent the rupee tumbling against the U.S. dollar.

Australia's S&P/ASX 200 fell 8.3% to 3,960.70, and New Zealand's NZX 50 index gave up 4.7% to 2,805.31. South Korea's Kospi lost 4.1% to 1,241.47 and Thailand's SET Index shed 8.7% to 456.74.

The Taiwanese market was closed for a holiday.

"I think people are trying to liquidate positions, but there just aren't any buyers there. It's the nature of the markets that there are very few people willing to buy stocks," said Andrew Sullivan, a sales trader at Main First Securities. "A lot of people sitting on cash are happy to be sitting on cash at the moment."

Sullivan added that the selling in Tokyo was likely intensified because Monday is a holiday there and markets are closed.

Regional detail

In Tokyo, banking giant Mizuho Financial Group MFG, -4.79% (8411), steelmaker JFE Holdings (5411), shipping company Mitsui O.S.K. Lines (9104), telecommunications major NTT DoCoMo (9437), pharmaceutical company Eisai co. (4523) and machinery maker Fanuc (6954) were among those whose shares lost 10% or more during the session.

A continued flow of bad news about global financial companies added to investor fears. Earlier in the day, Japan's Yamato Life Insurance Co. filed for bankruptcy protection from creditors, reportedly becoming the first in the industry to do so in seven years.

In Sydney, shares of BHP Billiton (BHP) BHP, -2.16% fell 7% and Commonwealth Bank of Australia (CBA) CBAUF, -0.23% lost 6.7%.

In Hong Kong, shares of market heavyweight HSBC Holdings (5) HBC, +0.72% tumbled 7%, while property major Sun Hung Kai Properties (16) SUHJY, -0.62% skidded almost 12%. In Singapore trading, shares of DBS Group Holdings DBSDY, -1.91% lost 9.1%.

In Mumbai, Icici Bank IBN, +0.30% shares plummeted nearly 18% amid worries about the impact of the global financial crisis on the lender. Infosys Technologies INFY, -0.51% dropped 4.7% after the software major cut its annual earnings-per-share forecast.

Regional insurance stocks also slumped in line with the broad markets, ignoring assurance from credit-rating company Standard & Poor's that Asia's insurance industry "has sufficiently strong fundamentals to withstand the current turmoil in the world's financial markets."

Shares of China Life Insurance Co. LFC, +0.17% (2628) tumbled 13% in Hong Kong, while Sompo Japan Insurance Inc. (8755) lost almost 12% in Tokyo.

In Asian currency trading, the U.S. dollar bought 98.99 yen, compared with 100.67 yen late Thursday. Against the Indian currency, the U.S. dollar jumped to 48.53 rupees, compared with 48.01 rupees late Wednesday.