BANGKOK -- The Tokyo stock market plunged Monday, its first business day after an earthquake and tsunami of epic proportions laid waste to cities along Japan's northeast coast, causing tens of billions of dollars in damage. Other Asian markets were mostly down. Oil prices dropped to near $99 a barrel after the disaster threatened to send the world's third-largest economy into recession, crimping demand for crude. In currencies, the dollar was down against the yen and the euro. The benchmark Nikkei 225 stock average dived 633.94 points, or 6.18%, to close at 9,620.49 -- wiping out gains made in 2011 while hitting its lowest level in four months. Worries about the economic impact of Friday's disaster, including massive power shortages that could disrupt factories, triggered a broad selloff that hit all sectors. The broader Topix index was down 7.5%. Shares of several major companies were overwhelmed with sell orders and had yet to trade. Among those, the Tokyo Electric Power , was set to fall by double digits as it struggled with malfunctioning nuclear reactors and a power shortage that led the company to announce rolling blackouts in parts of Tokyo and its suburbs. Companies with nuclear power-related businesses such as those that build nuclear power plants, registered staggering losses, including Hitachi ( HIT), down 16.2%, and Toshiba, down 16.3%. Mitsubishi Heavy Industries slumped 10% and Kobe Steel skidded 6.4%. Stocks in other sectors also took major hits as investors dumped shares over concerns about economic production and consumption. Car makers slid as northeastern Japan is a major center for auto production, complete with a myriad of parts suppliers and a network of roads and ports for efficient distribution. Major manufactures halted production around the country. Toyota ( TMC) , the world's largest automaker, fell 7.9%; Honda ( HMC) lost 6.5%; and Nissan ( NSANY) dropped 9.5%. Insurance companies -- many of which will likely face heavy claims for lost property and infrastructure -- also suffered sharp drops, including Tokio Marine Holdings, down 12.4%. Cosmo Oil, whose refinery has been on fire since the 8.9-magnitude quake, slid by a withering 21.6%. Analysts said the prognosis for Japan's economy in the near term depended heavily on whether it could stave off reactor meltdowns at the stricken Fukushima Dai-ichi nuclear plant. Four nuclear plants in northeastern Japan have reported damage, but the danger was greatest at the Dai-ichi plant.
"All estimates, economic and humanitarian, plainly remain contingent on the resolution of difficulties at nuclear power facilities, where two reactors are believed to have experienced partial meltdowns. Authorities have been pumping seawater into the facilities to replace coolants lost in the earthquake and thus prevent further meltdown. The degree to which this has been successful remains vague," analysts at DBS Bank in Singapore said in a report. Meanwhile, industrial and materials companies rose on expectations that they will benefit from Japan's rebuilding efforts. Japanese construction company Kajima soared 22.2% and Nishimatsu Construction jumped 19.3%. Elsewhere, Hong Kong's Hang Seng Index lost 0.2% to 23,204.06 while South Korea's Kospi was up 0.8% to 1,971.23. Mainland China's Shanghai Composite Index rose less than 0.1% at 2,935.41. The Shenzhen Composite Index of China's smaller, second exchange rose 0.9% to 1,310.99. Shares in Taiwan, Singapore, Australia, New Zealand and the Philippines were lower. Benchmarks in Indonesia and Thailand rose. Earlier Monday, the Bank of Japan injected a record 15 trillion yen ($183.8 billion) into money markets to try to defend the already fragile economy. By flooding the banking system with cash, the central bank hopes banks will continue lending money and meet the likely surge in demand for post-earthquake funds. A one-day policy meeting of the central bank is scheduled to end later Monday. The prospect of falling oil demand from Japan sent crude oil prices down $1.57 to $99.59 a barrel. In addition to the earthquake, oil prices fell after a scheduled day of protests in Saudi Arabia only drew a few hundred people. Oil traders have been worried the violence in the Middle East and North Africa would spread to the world's No. 1 oil exporter. Benchmark crude for April delivery was down $1.79 at $99.37 a barrel in electronic trading on the New York Mercantile Exchange. The contract lost $1.54 to $101.16 on Friday. The yen dove briefly after Friday's quake, but then recovered. The dollar was lower against the yen at 82.07 on Monday after hitting a three-week high of 83.30 yen in the immediate aftermath of the earthquake. The euro fetched $1.3933 from $1.3890 late Friday.