Stocks Gain on Sears Deal, But Trim Gains  NEW YORK (Reuters) - U.S. stocks advanced on Wednesday  after Kmart's plan to buy Sears in an \$11.5 billion  deal was  announced and computer maker Hewlett-Packard Co. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=HPQ.N target=/stocks/quickinfo/fullquote"&gt;HPQ.N&lt;/A&gt; posted  solid earnings, but higher oil prices prompted some investors  to sell equities.