The most important investment decision of the next decade might not be which stocks investors own. It might be how much of each stock they own . That's the fascinating argument emerging from new Bank of America valuation work comparing the traditional capitalization-weighted S&P 500 with its equal-weight counterpart. The conclusion is striking. Bank of America's normalized valuation model puts the traditional S&P 500 at approximately 32 times normalized earnings , a level historically associated with roughly negative 3% average annual returns over the following decade . The S&P 500 Equal Weight Index, meanwhile, trades at approximately 25 times normalized earnings , which the same framework associates with roughly positive 3% annualized returns . That's a six-percentage-point difference in projected annual performance. Compounded over ten years, the implications become enormous. And investors don't need to abandon the S&P 500 to make the switch. They sim...