The broad U.S. Standard & Poor's 500 index had its biggest weekly fall since July 2002 last week and is down 15.3% from its peak close on Oct. 9.
The Dow Jones industrial average is off 8.8% for the year. The S&P 500 index is down just under 10%, and the Nasdaq composite has fallen 11.8% in 2008.
If U.S. stocks open on Tuesday at the levels futures are indicating, it would push the market dangerously close to bear market territory — or a 20% drop from their peak in October. That would mark the end of the bull market that began in early October 2002.
"We're going for some tough slugging here," said Paul Nolte, director of investments at Hinsdale Associates in Hinsdale, Ill.
Dow Jones industrial average futures dropped 546 points or 4.5%. Should the Dow close lower on Tuesday by the amount the futures suggest, it would rank as the fourth-largest point loss ever for the index.
S&P 500 futures were down 62.5 points, or a 4.7% drop, far below fair value, a mathematical formula that evaluates pricing by taking into account interest rates, dividends and time to expiration on the contract. Nasdaq 100 futures slid 77.5 points, or 4.2%.
One major stock index, the Russell 2000 index of small-cap stocks, fell into bear market territory last week.
Since the start of the year, Japan's Nikkei index has declined 13%, while Hong Kong's blue-chip index is down more than 14%. Even China's Shanghai index — which nearly doubled last year — has fallen 6.6% since the beginning of the year and nearly 20% from its all-time closing high on Oct. 16.
"We've taken our lead from the Asian markets who have not been impressed by the U.S. There's debate if there's going to be a recession in the U.S. I don't think there's much chance of that though," said Richard Hunter an analyst at Hargreaves Lansdown Stockbrokers in London.
Concerns about the outlook for the U.S. economy, a major export market for Asian companies, has sent the region's markets sliding in 2008. Just last Wednesday, Hong Kong's blue-chip Hang Seng index sank 5.4%.
"It's another horrible day," said Francis Lun, a general manager at Fulbright Securities in Hong Kong. "Today it's because of disappointment that the U.S. stimulus (package) is too little, too late and investors feel it won't help the economy recover."
Japan's benchmark Nikkei 225 index slid 3.9% Monday to 13,325.94 points, its lowest close in more than 2 years. China's Shanghai Composite index plunged 5.1%.
India's benchmark stock index tumbled 7.4%, while Hong Kong's Hang Seng index plummeted 5.5%, its biggest percentage drop since the Sept. 11, 2001, terror attacks.
"People are certainly nervous about a potential recession in the U.S. spilling over to the rest of the world," said David Cohen, Director of Asian Economic Forecasting at Action Economics in Singapore.
"Maybe there's still some wariness about politicians are able to come up with a compromise and act sufficiently quickly" on a stimulus package, Cohen said. "I think the impact would be marginal anyway."
Investors took cues from the negative reaction to the president's plan on Wall Street on Friday, when the Dow Jones industrial average slid 0.5% to 12,099.30, bringing its loss for the year so far to nearly 9%.
Traders also have shrugged off assurances from Federal Reserve Chairman Ben Bernanke that the U.S. central bank is ready to act aggressively — which means a likely big interest rate cut later this month — to help the sagging economy.