Tanking Crude, Boeing Smack Dow Jones Industrial Average

The Dow Jones Industrial Average (INDEXDJX:DJI) has pulled back from Friday's notable milestone on this M&A Monday, as a steep drop in crude oil -- and an analyst-induced decline for Boeing Co (NYSE:BA) -- weigh on the blue-chip barometer. In fact, crude for April delivery was last seen down 2.8% at $49.38. Meanwhile, a disappointing reading on existing home sales is only stoking the bearish flames. Looking ahead, traders will be eagerly anticipating today's outcome of Greece's debt drama, as well as Fed Chair Janet Yellen's trip to Capitol Hill tomorrow.

Continue reading for more on today's market -- and don't miss:

• One sector that's "displaying clear leadership," courtesy of Schaeffer's Senior VP of Research Todd Salamone.
• A nearly $2 billion announcement from this tech titan has the stock trading in uncharted territory.
• Plus ... Checking in on the CBOE Volatility Index (VIX), the SPDR S&P 500 ETF Trust (SPY), and other noteworthy stats at midday.

Among the stocks with notable call volume is pharmaceutical firm Salix Pharmaceuticals, Ltd. (NASDAQ:SLXP), with the contracts crossing the tape at 17 times the average intraday pace. It appears a number of speculators are selling to open the equity's April 160 call, while others are buying to open SLXP's March 160 call. At last check, the stock was down 1.2% at $155.97, after Valeant Pharmaceuticals Intl Inc (NYSE:VRX) earlier agreed to purchase SLXP for about $158 per share.

For more midday statistics and stocks on the move, head to page 2.

Drugmaker Celldex Therapeutics, Inc. (NASDAQ:CLDX) is one of the biggest gainers on the Nasdaq. At last check, the stock was up 16.9% at $24.79, following some well-received news from the Food and Drug Administration (FDA). Although today's rally helped CLDX barrel through previous congestion in the $24 area, the stock is meeting resistance near $25 -- a neighborhood that capped the equity's advances last March.

China-based sports lottery issue 500.com Ltd (NYSE:WBAI) is one of the leading laggards on the Big Board. The stock has shed 17% to trade at $13 -- and earlier notched an all-time low of $12.52 -- even after WBAI rebuffed rumors that the Chinese government may revoke its license. Today's negative price action is just more of the same for a stock that's surrendered more than three-quarters of its value since hitting a record peak of $54 last March.

The CBOE Volatility Index (VIX) is up 0.6 point, or 4.3%, at 14.91.

Today's put/call volume ratio on the SPDR S&P 500 ETF Trust (SPY) is 1.76, with puts having the edge over calls. SPY is down 0.1 point, or 0.1%, at $211.11.