It has been a very mixed week for world equity markets. Although some major US indices have continued to rally to all-time highs, including the S&P 500 and the NASDAQ, these highs have been marginal, suggesting upward momentum is slowing. Gains have been concentrated in a shrinking number of large cap stocks, mainly in the semiconductor sector. In this edition of Equity Leaders Weekly, we look at concentration in the US equity market and the ongoing selloff in Europe.