YAHOO [BRIEFING.COM]: Intense selling sent the S&P 500 to its worst single-session loss in six months as participants pared risk amid rising social and political tension in the Middle East and Northern Africa.

Ongoing protests and social unrest in Libya prompted the country's leader, Gaddafi, to threaten suspension of oil supplies from his country, which boasts the biggest oil reserve in Africa. Gaddafi was also defiant in the face of calls for him to step down as dictator.

Asia's major averages led an overnight sell-off that saw the Shanghai Composite drop 2.6%, the Hang Seng slide 2.1%, and the Nikkei tumble 1.8%. News that Moody's lowered its outlook on Japan to Negative darkened the tone of trade.

The overnight slide combined with concern about volatility related to rising geopolitical risk abroad stirred U.S. participants to slash their stock holdings. At first, their efforts took stocks down about 1%, but as has been the case in previous sessions some stepped in to provide support and bid up the dip. A February Consumer Confidence Index reading of 70.4, which exceeded the Briefing.com consensus of 67.0 to set a near three-year high, aided the effort.

However, in contrast to previous sessions, sellers redoubled their efforts after stocks failed to extend their morning rebound. Persistent pressure took the S&P 500 to its first 2% loss since last August.

More than 90% of the stocks in the S&P 500 ended the day in the red. The bleeding brought in plenty of participants, who sent share volume well above 1 billion on the NYSE. Among the major sectors, materials were hit the hardest. As a group, materials stocks dove to a 3.1% loss. Energy had been resilient in the early going, but weakness inevitably bled into the space as the broad market buckled. Energy stocks had been up as much as 1.5%, but ended the day with a 0.7% loss.

Early strength in the energy sector was predominately underpinned by a spike in oil prices. April crude oil finished 6% higher at $95.32 per barrel. Elsewhere in the commodity space, safety seekers sent April gold up 0.9% to $1401.10 per ounce and silver 2% higher to $32.86 per ounce. Silver prices had actually set a new 30-year high above $34 per ounce in the early morning.

Treasuries also benefited from an interest in safety, despite lackluster results from an auction of 2-Year Notes. The auction drew a bid-to-cover of 3.03 for dollar demand of $106.1 billion, and an indirect bidder participation rate of 31.2%.

The dollar did little today. It had been flat in morning trade, but mustered a gain of merely 0.2% by the end of the day.

Corporate news had no real impact on overall trade. The spike in volatility -- the Volatility Index was up about 30% at its high -- caused many to shrug off earnings from Dow components Home Depot (HD 38.09, -0.39) and Wal-Mart (WMT 53.67, -1.71). Both bested what Wall Street had expected for the bottom line, but HD complemented its report with increased guidance and an increased dividend.

Commodities finished mixed on the session, with sizeable moves in both directions. Grains shed -5.4% to lead all decliners, while energy rallied for 2.8% to lead all advancers. Tensions in the Middle East factored in the direction of trade in numerous commodities.

May wheat shed 7% to close at $7.96 per bushel, May soybeans dropped 5.1% to end at $13.11 per bushel, while May corn settled lower by 4.2% to $6.90 per bushel. Prices were helped lower by a flight to safer asset classes amidst all the uncertainty surrounding events in the Middle East.

April crude oil finished higher by 6% to $95.32 per barrel. Again, concerns about the unrest in OPEC-member Libya and fears that protests could spread to other oil producing countries, supported prices throughout the session. Prices did, however, finish well below its overnight highs at $98.48. March natural gas shed 0.1% to finish at $3.87 per MMBtu.

A flight to safety helped precious metals finish higher today. April gold ended up 0.9% to $1401.10 per ounce, while March silver rallied for 2% to finish at $32.86 per ounce.

Advancing Sectors: (None)
Declining Sectors: Materials (-3.2%), Financial (-3.1%), Industrials (-2.9%), Tech (-2.6%), Consumer Discretionary (-2.4%), Telecom (-1.7%), Health Care (-1.5%), Energy (-0.7%), Consumer Staples (-0.7%), Utilities (-0.3%)DJ30 -178.46 NASDAQ -77.53 NQ100 -2.9% R2K -2.6% SP400 -2.4% SP500 -27.57 NASDAQ Adv/Vol/Dec 374/2.12 bln/2306 NYSE Adv/Vol/Dec 359/1.11 bln/2701