Marsh   McLennan: 5 Top Execs Leave Board  NEW YORK (Reuters) - 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;, the  insurance broker accused by New York's Attorney General Eliot  Spitzer of bid-rigging fraud, on Thursday said five senior  executives stepped down from its board of directors.