Everyone is staring at their screens in disbelief

We are headed for a bad opening going by the futures. As of 6 AM all three indexes are showing 6% plus down move. We are now in really unknown territory. Just hold on to your nerves and wallet.

LONDON (MarketWatch) - U.S. stock futures pointed to another monumental beating on Friday, as a plunge in Asia reignited concerns about the health of the global economy.

S&P 500 futures dropped 60 points to 855.20 and Nasdaq 100 futures fell 81.5 points to 1,172.00. Dow industrial futures fell 538 points.

The drop on the S&P 500 contract was so much that it triggered a halt in electronic trading.

Thursday's session for U.S. stocks was erratic but generally positive, with the Dow Jones Industrial Average closing 172 points higher and the S&P 500 rising 11 points, though the Nasdaq Composite slipped 11 points.

But that wasn't the case in Asia, where the Nikkei 225 tumbled 9.6% in Tokyo as Japanese traders got their first chance to react to Sony's profit warning, and the Kospi plunged 10.6% in South Korea. Europe stocks also were crushed, with the Dow Jones Stoxx 600 losing 6.6%.

"Everyone is staring at their screens in disbelief," said Tom Hougaard, a strategist at City Index in London.