Bullish on Wall Street: What it Means for Investors.

The S&P 500 rose 0.6% on Thursday, putting the benchmark index up 20% from its Oct. 12 closing low and heralding the start of a new bull market, at least by the definition of some market participants. However, there is no set definition of a bull or bear market, and even the commonly accepted definition of a 20% rise off a low for a bull market is open to interpretation. Some market analysts require a low to remain intact for a duration of at least seven months to remove the risk of a quick reversal lower after a rally of 20% or more. Others require a broad participation across sectors, something lacking in the current rally as most of the gain in the S&P 500 this year has been concentrated among a small amount of very large stocks.