Returns are driven by earnings growth and valuation expansion . The article only looks at a specific time frame which favours significantly the rebound of tech.

Returns are driven by earnings growth and valuation expansion . The article only looks at a specific time frame which favours significantly the rebound of tech. Looking at a longer time frame the returns are also not as normally distributed across stocks, but buying the index is the best way to capture the market return in aggregate without being exposed to sector risk.