Buy an index fund The first option, while boring, is historically proven to work: Buy an index fund, such as the SPDR S&P 500 ETF (NYSEMKT: SPY) . With an historic annual return of 7%, inclusive of dividend reinvestment and when adjusted for inflation, the stock market remains one of your top investment choices. Purchasing an ETF gives an investor access to instant diversification within an industry or sector, based on market cap or even on geographic location.