Given all of the green on the screen during these days, this could be a good time to think about what big up days usually mean. Typically, they occur when the market has already run into trouble, and are often technical in nature. An analysis by Michael Batnick at The Irrelevant Investor, showed that 22 of the 25 best days since 1970 occurred under the 200-day moving average. That implies they were oversold rallies with some element of short covering. Traders may like them, but long-term investors would much rather see three 100-point days than one 300-point day. The more gradual gains reflect a healthier accumulation and not a reflexive reaction.