By subdividing private property into miniscule shares, capitalism has allowed the masses to own the means of production in a way that socialism never could.
The stock market numbers give us the sum-total of millions of individual decisions, which form an aggregate that affects the whole economy. The stock market also lets us see the laws of price and demand and other economic forces working seemingly instantaneously.
Anyway, yesterday on Wall Street was something to behold: Following a world-wide collapse on the previous day, when the American markets were closed, stocks, as predicted, followed that trend, dropping 300 points. But then, people seeing that they could get blue-chip properties really cheap, started buying. And buoyed by an interest rate cut from Treasury, they kept buying. The market ended 300 points up. That would be 600 points from what it was in the middle of the day!