The true value of a share of a stock is based on the price of the share of stock in relationship to what it earns. If the stock market goes up the true value of the stock goes down. When the stock market goes down the true value goes up.
When a stock is first sold by a corporation to raise money that is all the corporation gets out of it. Whether the stock goes up or down does not matter, it should have nothing to do with the corporation ability to produce goods and services.
Public traded corporations are nothing but poker chips for the wall street traders. The shares of stock are juggled up and down to keep the gambling house open. Sometimes the wind blowing east will blow the price of a chip up and sometimes it will blow it down.
The ten thousand Public traded corporations are not the backbone of the American economy. Over thirty million private businesses are the real bedrock of the economy. If Wall Street closed its doors tomorrow, the American economy would keep on ticking. Even the underground economy is more important than Wall Street.