On Friday, Goldman Sachs (GS) released a research note suggesting that the S&P 500 is likely to deliver an annualized return of just 3% over the next 10 years. The report pointed to the market concentration issue, with more than a third of the index being invested in just 10 stocks, a pattern that has historically led to below-average returns (read: Is S&P 500 Expected to Underperform? ETFs in Focus).High Market Concentration RisksBen Snider, an equity strategist at Goldman Sachs, emphasized that while the ...