Blue Chips Unchanged, Wal-Mart Weighs  NEW YORK (Reuters) - U.S. blue chips were near the  unchanged mark on Monday as a disappointing sales forecast from  retailer Wal-Mart Stores Inc. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=WMT.N target=/stocks/quickinfo/fullquote"&gt;WMT.N&lt;/A&gt; dampened sentiment,  offsetting the benefit of easing oil prices.