Approaches to determining stock values vary, but fundamentally, each company judging itself undervalued is saying that its future stream of earnings justifies a higher price than the stock market is willing to accord it.

If a company's stock is undervalued - as many managers believe theirs is - a repurchase may offer the best payoff of all.

The most important thing is that the stock market had declined to levels that were arguably undervalued, and that many aggressive managers also realized there was a great deal of pessimism.

In the 1987 stock market crash, according to the conclusions of the official Brady report, colossal sales of stock index futures by so-called portfolio insurers - whose investment strategies depended entirely on these derivatives - greatly exacerbated the 500-point market decline.

The stock market clearly values companies that can deliver disruptive innovation.

The stock market never sleeps,even in a blinding market recession it continues to thrive for those who know how to see opportunities.