Two phenomenal businesses with extremely bright futures are currently valued at single-digit forward-earnings multiples.Over the long run, Wall Street is a wealth-building machine. When compared to other asset classes, such as bonds, housing, and commodities (e.g., oil and gold), nothing comes remotely close to the annualized returns that equities have delivered over the last century.But this doesn't mean stocks move up in a straight line.The first three trading sessions of August featured the growth-stock- ...