This is the VOA Special English Economics Report.

Big stock exchanges in the United States are linked in what is known as the national market system plan. The idea is to process deals and report the best available prices to the public as quickly as possible.

But there are other ways of investing that operate outside the national market system.

In the late nineteen nineties, the Securities and Exchange Commission wanted to make room for new ideas in financial trading. The commission developed new rules for exchanges and for what are known as alternative trading systems.