U.S. stock concentration – it's not all doom and gloom

U.S. equity market concentration is, by some measures, now the strongest ever, raising justifiable concerns that having the entire market's fate in the hands of so few stocks will only end in tears. The current environment highlights a lack of diversification and risk-spreading options, fuels bubble speculation, and makes it difficult for active and even passive managers to beat the benchmark index when the juggernaut is being driven by literally a handful of stocks. But it's not necessarily an accident waiting to happen. From a global historical perspective Wall Street's dynamics today are not without precedent, average returns tend to…