"We're experiencing continued fallout from the negative momentum we've endured for almost two weeks now," suggested Schaeffer's Senior Equity Analyst Joe Bell. "Throw in the very poor Philly Fed's manufacturing index this morning, and sellers once again pushed this market down." With that, the Dow Jones Industrial Average (DJI) marked its fifth consecutive session lower, and its first daily close below its 140-day moving average since Nov. 29.

Keep reading to see what else was on our radar today:

• Lagging market got you down? Head for the biotech sector.
• Beware the slow, steady drop in the SPDR S&P 500 ETF Trust (SPY).
• Will the Street get a boost from the recent oversold conditions?

The Dow Jones Industrial Average (DJI – 12,442.49) suffered its worst daily close since Jan. 13, plummeting 156.1 points, or 1.2%. The Dow closed just above its session low of 12,440.52, tagged in the last minutes of trading. All but six blue chips finished with losses, as Caterpillar's (CAT) 4.4% drop led the parade of underperformers. Wal-Mart's (WMT) earnings-induced bounce of 4.2% paced the winning issues.

The S&P 500 Index (SPX – 1,304.86) slipped back below the 1,330 level today, and burned off 19.9 points, or 1.5%, by the time the dust settled. The Nasdaq Composite (COMP – 2,813.69) turned in the worst performance of its peers, declining 60.4 points, or 2.1%.

The CBOE Market Volatility Index (VIX – 24.49) touched its highest daily settlement since Dec. 19, vaulting nearly 10% today. The VIX closed just below its late-session high of 24.51.

Today's highlight: The broad-market sell-off today was caused in part by the usual suspects in the euro zone and a couple of disappointing domestic economic reports. "Although it might not mean much for the overall market, we are zeroing in on Facebook's (FB) IPO tomorrow," said Bell. "It just might give us a welcome distraction from the slow grind lower we can't seem to escape."

Turning to today's major market stories...

• Schaeffer's Equities Analyst Bryan Sapp pondered the absence of panic surrounding the faltering SPX.
• As Wall Street tows a bumpy road, the biotech sector continued to shine.
• Last minute May-dated call volume swelled on Google (GOOG).
• Put players wagered on prolonged pullbacks in Freeport-McMoRan Copper & Gold (FCX) and Urban Outfitters (URBN).
• Internet-based businesses Ctrip.com (CTRP) and E*Trade Financial (ETFC) were tapped with brokerage notes today.
• Contrarians could find a comfy ride with AutoZone (AZO), General Motors (GM), and Garmin (GRMN).
• Ahead of tomorrow morning's earnings, call activity surged higher on Ann (ANN).
• An options trader executed a bear put spread on struggling First Solar (FSLR).
• New highs and new lows: Array BioPharma (ARRY) and MEMC Electronic Materials (WFR) were among the equities making record-breaking moves today.

For today's activity in commodities, options, and more, head to page 2.