While most online brokers do not offer international trading, some do. Nearly every broker supports trading American depositary receipts (ADRs), which offers US investors an easy, simple way to invest in foreign companies. However, if you want to buy physical shares of an international company, then you need to do your research. Interactive Brokers is the leader in this space but is built for professionals. For casual investing, both Fidelity and Charles Schwab offer international stock trading.
The trading products you can purchase using these platforms can include stocks, commodities, derivatives, bonds etc. which can be traded between the traders on the stock market with intermediates such as investment banks, stock exchanges, brokers and market makers. A communication network is set-up between the various intermediates and the traders, which facilitates proper execution of the whole system.