The most popular ETF of these retail investors tracks an index that hasn't had a negative total return over any rolling 20-year period since the start of the 20th century.

For more than a century, stocks have stood atop the pedestal as the premier wealth creator. While commodities, real estate, and bonds have done their part to increase the nominal wealth of investors, stocks have maintained the highest average annual return of the bunch.

But just because stocks have outperformed, it doesn't mean equities move higher in a straight line. In fact, things can get downright dicey on Wall Street from time to time.

Earlier this year, the benchmark S&P 500 ( ^GSPC -2.71% ) , iconic Dow Jones Industrial Average ( ^DJI -1.90% ) , and growth stock-dominated Nasdaq Composite (

See Full Page