The indices ended up on the day, but you wouldn't know it by the afternoon part of the session, which was very ugly and steeply lower. The day started out with a big gap-up. They ran hard in the morning, got to the highs for the session right around noon. Lunch hour was spent pulling back and after lunch hour they tried to rally, which failed and rolled over. At that point they had the appearance of intraday mini head-and-shoulders tops. When the necklines on those tops were broken, the indices accelerated even sharper, and in the last hour in particular the sell-off was steep.

The Dow was up 35.6 today, but that was more than 100 points off the high for the session. The S&P 500 was up about 3, and some 12 points of its high. So, big sell-offs across the board in the afternoon gave back most of the gains for the day. The SOX managed to gain 1 percent, or 5.53, and that was about 8 points off the earlier high.

One of the clues to today's drop was that technicals were rather weak and advance-declines on Nasdaq in particular were down near the price peak of the day, which was very ominous. That negative technical divergence resulted in the afternoon sell-off.

The advance/declines ended up about 17 to 16 negative on New York but more than 3 to 2 negative on Nasdaq and by more than 800 issues. Up/down volume was about 3 to 2 positive on New York, and about 11 to 7 negative on Nasdaq. Total volume of just under 1.9 billion on Nasdaq, with New York at about 1 2/3 billion.

TheTechTrader.com board was active. A lot of stocks that were up in the morning gave it back and closed down on the day. The leader of the day was Optelecom-NKF (OPTC), up 3.10 on nearly 1/2 million today. Rediff.com India (REDF) snapped back 1.45 on rumors of a Google (GOOG) takeover, and Sify Ltd. (SIFY) was up 1.18 in sympathy.

Neoware Systems (NWRE) bounced back 59 cents, PW Eagle (PWEI) up nearly a point, LanOptics Ltd (LNOP) up 81 cents, Dynamic Materials Corp. (BOOM) advanced 88 cents, and DXP Enterprises (DXPE) up 67 cents, after hitting a new all-time high this morning.

In the large-cap sector, Broadcom (BRCM) advanced 1.82.

On the downside, loss leader was Energy Conversion Devices (ENER), which was over 50 earlier in the session, but closed around 48, down 1.15 today. Stereotaxis (STXS) gave back 39 cents, Novavax (NVAX) 36 cents, LVLT 31 cents, Ionatron (IOTN) 32 cents, and Eclipsys (ECLP) down 74 cents, with Endwave (ENWV) down 77 cents as well. BioCryst Pharmaceuticals (BCRX) also gave back 56 cents.

Stepping back and reviewing the hourly chart patterns, initial support was broken today as indices plunged in the afternoon, closing at the lows for the session. But much more formidable key support is just below here at 1700 NDX and at 1294-5 zone on the S&P 500.

We'll be watching that carefully tomorrow morning to see if they can hold them here and move higher, or whether this afternoon's sharp pullback was the beginning of something worse.

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.