07/16/2013 02:22 pm ET | Updated Sep 15, 2013

Market Microstructure and High-Frequency Market Manipulation

Many investors are rightfully concerned about market manipulation -- after all, who wants to be taken for a ride? High-frequency market manipulation proved to be particularly disconcerting to many investors as it is evolutionary, difficult to detect without appropriate tools, and is still not universally understood. Adding even more complexity to investor decision-making is the explosion of various types of exchanges and other alternative trading venues, some known as dark pools. As my latest research shows, however, certain types of trading venues can be more suited to specific classes of investors. Investors may further select to trade on venues that minimize undesired market characteristics, including high-frequency market manipulation.

In the U.S. today, there are 16 exchanges for equities, commodities and options, as well as countless alternative trading venues (ATS) that include lightly regulated dark pools and brokers' own "internalizers" -- matching engines that trade offsetting orders placed by a broker's customers. Each trading venue has its own approach to placing orders and navigating the methodologies is no easy feat. Among equity exchanges, for example, some use price-time priority and some pro-rata. Within the price-time priority category, some platforms are known as "normal," while others are "inverted." The differences are non-trivial, but luckily, not complicated, as I discuss in my new book, High-Frequency Trading: A Practical Guide to Algorithmic Strategies and Trading Systems, 2nd edition.

"Normal" exchanges charge customers for placing "I-want-it-now-at-the-best-available-price" market orders and pay, yes, pay for "I-want-it-anytime-but-at-a-certain-price" limit orders. Inverted exchanges do the opposite: they charge for placing limit orders, yet compensate traders placing market orders. Both normal and inverted exchanges execute limit orders based on their respective price-time priority: the best-priced limit orders are executed before the worse-priced limit orders, and within each price queue, first-arrived limit orders are processed before limit orders that arrive later. In pro-rata markets, all best-priced limit orders are executed partially at the same time in equal proportion. Normal exchanges include NYSE, Direct Edge and BATS. NASDAQ Boston OMX, Direct Edge A, and BATS Y count among the inverted exchanges. Philadelphia stock exchange was operating under a pro-rata schedule until May 2013.

What my research shows is that pro-rata exchanges are the least susceptible to high-frequency market manipulation, while the normal exchanges are the most conducive to the said manipulation, with inverted exchanges falling somewhere in between, depending on their pricing. In a nutshell, the likelihood of manipulation is stemmed by potential costs of manipulation, be it the costs of being discovered, or the costs of executing an unintended trade. Furthermore, what my research shows is that the differences among the exchanges do not stop at market manipulation, but go much deeper into other areas frequently of concern to investors: market volatility, probability of market crashes and available liquidity. It turns out that structurally different markets exhibit different characteristics as far as all of these metrics are concerned.

The normal exchanges tend to be more volatile and more prone to market crashes than their inverted and pro-rata brethren. As such, investors concerned about market manipulation may be best advised to execute their orders at inverted or pro-rata exchanges. At the same time, normal exchanges have built-in incentives for brokers to route their customers' orders there, making it all even more complicated!

Still, the explosion of exchange choices, however complex, gives today's investors an unprecedented ability to select their optimum exchange characteristics; fees, volatility, liquidity and probability of extreme events (crashes) being just a few of the parameters. For the first time in the history of financial markets, investors can choose the trading environment in which they feel most comfortable.