Stocks End Lower as Insurers, Oil Weigh  NEW YORK (Reuters) - U.S. stocks slid on Thursday after New  York Attorney General Eliot Spitzer accused insurance broker  Marsh   McLennan Cos. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=MMC.N target=/stocks/quickinfo/fullquote"&gt;MMC.N&lt;/A&gt; of fraud, and the fallout hit  insurers, including American International Group &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=AIG.N target=/stocks/quickinfo/fullquote"&gt;AIG.N&lt;/A&gt;.