Most retirees who own an S&P 500 index fund hold a portfolio dominated by mega-cap technology, with mid-sized businesses getting almost no weight despite making up a meaningful share of corporate America. That gap is the reason the Vanguard Mid-Cap ETF (NYSEARCA:VO) exists, and with roughly $94 billion in assets and a 0.04% expense ratio, ... Vanguard’s $94 Billion Mid Cap ETF Is Quietly Beating the S&P 500 With a Fifty Year Old Strategy