US&nbsp; STOCKS&nbsp; fell yesterday as signs of weakness in housing and investors' worries that authorities might be curbing stimulus efforts too soon sparked caution.<br /><br />World central banks said they would scale back infusions of US dollars into their banking systems, fueling unease triggered a day earlier when stocks sold off following the US Federal Reserve&rsquo;s decision to slow purchases of mortgage debt.<br /><br />That program has been one of the key pillars of the Fed&rsquo;s efforts to support mortgage lending.<br /><br />Thursday&rsquo;s losses drove the benchmark S&amp;P 500, which has rallied nearly 60 per cent in six months from 12-year lows, to its worst two-day drop in three weeks as investors pummeled stocks across the board.<br /><br />All 10 S&amp;P 500 sectors fell, with materials, energy, financials and industrials faring the worst.<br /><br />&ldquo;The housing number today threw some gasoline on the fire,&rdquo; said John Kosar, market technician and president of Asbury Research. <br /><br />&ldquo;It&rsquo;s not only that the recovery is fragile, but the other important story is just how far the market has come, so fast.&rdquo;<br /><br />The Dow Jones industrial average dropped 41.11 points, or 0.42 per cent, to 9,707.44. The Standard &amp; Poor&rsquo;s 500 Index fell 10.09 points, or 0.95 per cent, to 1,050.78. The Nasdaq Composite Index slid 23.81 points, or 1.12 per cent, to 2,107.61.