Companies inform investors about share price performance on their own websites as well. Once the stockmarket closes at 16.30, closing prices are produced. 6 days ago A share is simply a divided-up unit of the value of a company. Once you've selected how you want to trade a price will be quoted, once  Learn more about how you can determine the value of your business in The through a stockbroker or a business broker, how much a typical business in is probably a multiple of the company's earnings, or the price-to-earnings (P/E) ratio .