Utilize your financial knowledge, give your answer or opinion to the input question or subject . Answer format is not limited.

Trading on exchanges or via brokerage companies?
I was wondering what relations are between brokerage companies and exchanges? Are brokers representing investors to trade on exchanges? Yes...but a broker may also buy and sell stocks for his own account. This is called broker-delaer firm. For individual investors, what are some cons and pros of trading on the exchanges directly versus indirectly via brokers? Doesn't the former save the investors any costs/expenses paid to the brokers? Yes, but to trade directly on an exchange, you need to register with them. That costs money and only a limited number of people can register I believe. Note that some (or all?) exchanges have their websites where I think trading can be done electronically, such as NASDAQ and BATS? Can almost all stocks be found and traded on almost every exchange? In other words, is it possible that a popular stock can only be found and traded on one exchange, but not found on the other exchange? If needed to be more specific, I am particularly interested in the U.S. case,and for example, Apple's stock. Yes, it is very much possible with smaller companies. Big companies are usually on multiple exchanges. What are your advices for choosing exchange and choosing brokerage companies? What exchanges and brokerage companies do you recommend? For brokerage companies, a beginner can go with discount broker. For sophisticated investors can opt for full service brokers. Usually your bank will have a brokerage firm. For exchanges, it depends...if you are in US, you should send to the US exchanges. IF you wish to send to other exchanges in other countries, you should check with the broker about that.