Stocks Rally as Oil Prices Drop  NEW YORK (Reuters) - U.S. stocks extended their  post-election rally on Thursday, pushing the S P 500 to its  highest close for more than two years as oil prices tumbled  below \$49, while tobacco and food company Altria Group Inc.  &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=MO.N target=/stocks/quickinfo/fullquote"&gt;MO.N&lt;/A&gt; surged after saying it may split itself up.