The December rally, which was looking vulnerable as of Monday, managed to resume its trend before giving back some of those gains today. I'm still looking for a larger move back to retest breakout support, which may start today, but today's selling volume was well below recent buying - so the percentage loss looked worse than it actually was.
The Nasdaq Composite loss did little damage to the technicals, and relative performance continues to surge. The 20-day MA is crossing above the 200-day MA, so the 20-day MA is likely to be the first area of potential support to be tested should the current selling continues. 
The S&P 500 also enjoys a net bullish technical picture, although strength is not as robust as for the Nasdaq. More importantly, relative performance (vs. the Russell 2000) has been particularly weak - although it has improved over February. 
The Russell 2000 is underperforming against the Nasdaq but is still edging it over the S&P 500. Other technicals are net bullish, and the current pullback looks like a 'bull flag.'
The Dow Jones Industrial Average had been the high flyer, but the breakout, as happened in other indexes, has yet to occur. This is the index to buy if you were a trader looking for a breakout opportunity. I would be looking for a breakout here soon. 
I would be okay with further (low volume) losses for the remainder of the week. Still, I don't want to see a significant undercut of breakout support for any of the aforementioned indexes.
It may prove to be 20-day MAs that play a key role in marking an end to any extended decline that emerges from here.