The hardest part of retirement investing isn't picking stocks or timing the market - it's resisting the urge to do either. iShares Core S&P Total U.S. Stock Market ETF (NYSEARCA:ITOT) solves this by offering exposure to the entire U.S. equity market in a single position, charging just 0.03% annually, and requiring no ongoing decisions beyond occasional rebalancing with bonds. What ITOT Actually Does in a Retirement Portfolio