You don't need to go to a web page or even use the Stocks app for a quick look at a price. Just use Command+space to open Spotlight and type the symbol, like AAPL. You'll get the current price, a chart, and other information. You can also use the company name and the word "stock," which comes in handy for symbols that are too basic to be recognized as stocks, like "AT&T stock," or when you don't know the symbol. Click on the result and you go to the Stocks app. Works more or less the same way on iOS in search too.