Marsh  amp; McLennan to lay off 3,000 workers as it deals with fallout &lt;b&gt;...&lt;/b&gt; NEW YORK -- Marsh  amp; McLennan, the nation #39;s largest insurance brokerage, said Tuesday it will lay off 3,000 employees, or about 5 percent of its work force, because of fallout from a bid-rigging scandal that has engulfed the insurance industry.