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. Alternative trading systems are operated by brokers or dealers. They mainly serve big investors like retirement funds, universities and financial companies. These systems trade the same public stocks as other market players do. But they do not publicly report their trades. This secrecy explains why they also have another name: “dark pools.” As of October, there were eighty-six alternative trading systems registered with the Securities and Exchange Commission.A buy or sell order for a large amount of stock can move markets. It can influence other investors to try to buy or sell shares of that same stock. Supporters of alternative trading systems say the secrecy reduces the risk of a disorderly market. But the International Monetary Fund has concerns about alternative trading systems. It says they limit the ability of the investing public to price a security effectively. Also, the IMF says the activity of these trading systems is largely outside the reach of market regulators. Another alternative to the investing methods that most people know is the work of so-called angel investors. These are individuals who invest in new projects — and not just Internet startups that hope to become the next Google or Facebook. They could also be small, local businesses. Steve Moore made a lot of money in the software business. After he retired he made an interest-free loan to Crystie and Keith Kisler. The couple operate a small organic farm in Washington state. They could not get a bank loan to build their business.In return, Mr. Moore received a minority share of their business. The Center for Venture Research at the University of New Hampshire says angel investing fell more than six percent nationwide in the first half of last year. Still, angel investments during that period totaled eight and a half billion dollars.For VOA Special English I’m Alex Villarreal.