YAHOO [BRIEFING.COM]: The S&P 500 moved sharply lower in broad-based fashion, which took it below the key 900 level for the first time this month. With sellers in control, the session culminated in the stock market's worst single-session percentage loss in two months.

Declining issues outnumbered advancers by 10-to-1 in the S&P 500. Losses were steepest among financial issues, which shed 6.2% as they steadily descended throughout the entire session. Diversified financial services (-7.5%) and specialized finance (-7.3%) made up some of the weakest performing stocks in the financial sector. Financial stocks are down more than 7% month-to-date, but still up nearly 50% from their March lows, making them ripe for plenty more profit taking.

Energy stocks and materials stocks showed weakness for the entire session. The lost a respective 4.6% and 5.3% amid broader market weakness and a drop in commodities prices, which were undercut by a stronger U.S. dollar.

With the greenback up 0.7% against a basket of major foreign currencies, the CRB Commodity Index dropped 2.7% in its sharpest downward move in more than two weeks. Oil prices showed particular weakness; July contract prices shed 3.6% to settle at $67.06 per barrel before expiring, while August contract prices settled 3.8% lower at $67.33 per barrel.

The negative bias in the broader market certainly wasn't helped by news that the World Bank cut its forecast for major economies like that of the U.S. The news seemed to embolden the efforts of sellers, who just last week handed stocks their first weekly decline in five weeks. The latest selling effort led the S&P 500 to breach the 900 level, which marks the approximate intersection of the downward sloping 200-day moving average and the upward sloping 50-day moving average.

The only pockets of strength this session were found among defensive-oriented sectors. Utilities had been sporting enviable gains for most of the session, but surrendered them into the close and finished unchanged.

Telecom tacked on 0.5% as the only major sector to finish in the green.

Consumer staples stocks, also considered defensive, slipped 0.8%. Drug retailer Walgreen (WAG 29.64, -1.79) weighed on the group after posting quarterly earnings results that missed the consensus estimate.

Health care stocks, which have shown relative strength in recent sessions, fell 2.0%. Pharmaceutical stocks finished 1.5% lower amid news from The Wall Street Journal that the group will cut Medicaid costs as a proactive measure against more damaging industry reform.

There weren't any economic reports released today, but the release of May existing home sales data on Tuesday will start a steady flow of reports for the coming days. DJ30 -200.72 NASDAQ -61.78 NQ100 -3.0% R2K -3.9% SP400 -3.7% SP500 -28.19 NASDAQ Adv/Vol/Dec 415/2.32 bln/2264 NYSE Adv/Vol/Dec 345/1.40 bln/2703