Both. There are companies/corporations that do trade on the stock market that are traded on the stock market (Several US Markets), that are mostly US Companies. However, many companies are very international. For instance Intel is one of the largest Tech Stocks traded on the Nasdaq. However, Intel sells products and manufactures products from Processors to chipsets all over the world. Many companies like Exxon Mobil and British Petroleum are also world wide companies.
Many companies like Ford are based in the USA but they have parts manufacturers in many locations including USA, Canada, Mexico, etc. They sell products worldwide as well as domestically. Almost all companies are like that. Some companies like Banks and power supply companies have a lot of business that is mostly in the USA.
Walmart is thought to be a US company but they are building stores all over the world and also buy goods all over the world.
You can not live in a USA only fishbowl. It is impossible.
I can think of some stocks that are mostly US like Lowes (LOW), Home Depot, Target, Boeing??, Sears Holding (Sears and K-Mart) SHLD, some of these are retailers and they are on the stock market. So dont believe in the mindless dribble on the news and from your friends. Go Open a stock trading account and trade some stocks and learn something. You can open a Scotrade account for $500.00.
Bank of America stock was as low as $2.00. If you had purchased it for $2.00 you could have made a lot of profit. This week I noticed it was selling for $18.00. It may be lower now. That would have been a substantial profit margin. I think Century Twentyone Holding Company stock has sold for as little as $1.00 to as high as $4.00, but it will pay out a dividend of $0.16 per shars. Most of this information you can find on the Internet.
If you can sit around in the USA and make money off of Europe and Asia and Malaysia, then you can let their good economy help to bring ours up. This is progressive thinking. Arent liberals suppose to be progressive. Watch the Kudlow report or Mad Money.