(Bloomberg) -- While concern has grown in the past week that narrowing market breadth has tapped the brakes on the S&P 500 Index’s blistering rally, it turns out that stock bulls are still stepping in to snap up shares ahead of the Federal Reserve’s interest-rate decision.Most Read from BloombergHow California Sees the World, and ItselfThe index’s DVAN trend line — a proprietary divergence analysis that measures buying or selling pressure — has been on a buying streak since Election Day, with in