The S&P 500 beat both Dow, and Nasdaq in 2021 by the widest margin in 24 years. Here's what history says happens next year.

[unable to retrieve full-text content]Purchasers of U.S. stocks have danced to the tune of a record rise for the broad-market S&P 500 index in 2021 and are eager to glean clues on what follows in the coming year which many expect to be …