If you just want quotes, as Sitlet wrote, there are a ton of apps.
If you want more detailed quotes and news about your stocks, the best thing out there is Yahoo Finance web site. The problem is that it is best viewed on a large screen, and if you have a 3.25" diagonal phone, you won't like it much. And you have to view it in whatever browser you're using.
There's also a Yahoo Finance app, but it doesn't have the customization options available on the real thing. For example, on the summary page, you might like to have the price of gold instead of the 10-year interest rate. But you can't do that, or at least I haven't figured out how to do it. But it does do a decent job of giving you access to a wide range of company-specific news. And it will give you access to your Yahoo Finance portfolios that you've set up.
And it's free.