After doing some long-term market research, I've noticed that portfolios and individual issues can go down much further than they can shoot up. A good example of this is the crash of 87 -- which sent the index down over 20% in a short time. There has never been an example of an index going up 20% in a day, though. So, does this mean that humans are more susceptible to fear than to greed? Is fear the strongest motivator for market action?