Turnaround Tuesday with an exclamation point! The indices gapped down right at the get-go. Futures were already down, but when the ISM Index came out way below expectations the market plunged at the opening, rallied to form bear flags, and then stair-stepped lower the rest of the day, closing at the lows for the day going away.

Net on the day the Dow was down 370, the S&P 500 44, and the Nasdaq 100 over 55. The Philadelphia Semiconductor Index (SOXX) fell 14.37, a nearly 3 percent loss across the board for all the indices.

The technicals definitely confirmed how bad the day was. Declines led advances by 25 1/2 to 6 on New York, and by 23 to 6 on Nasdaq. But up/down volume was even worse, more than 12 to 1 negative on New York and a similar number on Nasdaq. Total volume was about 1 2/3 on New York, and a little more than 2.4 billion on Nasdaq.

TheTechTrader.com board was lower across the board, except for one stock that I follow. That's Chart of the Week Converted Organics (COIN), and even that was up just 8 cents, after being up 90 cents earlier in the session.

On the downside, leading the way was Sigma Designs (SIGM), down 6.43. DryShips (DRYS) fell 4.77, Excel Maritime (EXM) 3.49, and TBS International (TBSI) 2.76 in a very weak shipping group.

Solar energy stocks didn't fare much better, with Solarfun (SOLF) down 2.19, Ascent Solar (ASTI) down 93 cents, China Sunergy (CSUN) 59 cents, Canadian Solar (CSIQ) 1.77, and Energy Conversion Devices (ENER) down 1.27.

Other point-plus losers of note, a few members of the Boxer Shorts list had a very negative session. SII dropped 2.05, CVD 1.52, and IVGN 1.57.

Among other losses, Cepheid (CPHD) lost 1.82, China Natural Resources (CHNR) gave back 2.75, Chindex (CHDX) 1.33, China Finance Online (JRJC) 1.99, and RMBS 1.95. ULBI fell 1.52.

So a nasty day on Wall Street, and with the indices closing at the lows for the day going away, right near key short-term support. Tomorrow will be a vital session for the trend.

Harry Boxer is a technical consultant to many Wall Street hedge funds and large institutional traders, and author of TheTechTrader.com, a real-time diary of his day, swing and intermediate-term trades. For more of Harry Boxer, sign up for a free 15-day trial to his Real-Time Technical Trading Diary, or sign up for a free 30-day trial to his Top Charts of the Week service.