During a stock market rally we find difficult to comprehend, it somehow seems appropriate to publish a chart we’re almost at a loss to explain. The first chart shows the 90-year history of the trailing one-year (252-day) correlation of daily returns across market sectors. Correlations have been in a free-fall of late, and now appear to have a good shot at undercutting the all-time low established midway through the 2000-2002 bear market.