Wall Street has rewarded its most patient investors handsomely over the past 10 years. Is there more to come?

The S&P 500, the U.S. market's benchmark index, has gained about 309 percent since bottoming out at 676.53 points in March 2009 during the Great Recession, according to FactSet. The index is now 5.4 percent below its recent peak of 2,930.75 set on Sept. 20.

This bull market's lifespan, the longest on record, speaks to financial markets' resiliency in the face of a variety of shocks, including a brutal fourth quarter of 2018.

Whether the bull keeps running hinges on whether companies ca...