Cover Story: Keeping Watch
Traders Magazine Online News, May 7, 2012
Deutsche Bank can only view its competitors pools in the aggregate, of course. It cannot observe the behavior of the individual participants.
Besides price impact, the brokers also factor in other variables. Anyone coming into our pool must display certain characteristics and continue to meet several requirements in order to remain a participant, Inzirillo said. We have strict guidelines. Among about a dozen metrics, Merrill looks at average quote duration and the size people are willing to trade, for instance.
Most brokers also consider the nature of the liquidity provided when analyzing the activity in their pools. They look at whether a trader is providing liquidity or taking it.
Morgan Stanley will consult with participants it considers aggressive takers of liquidity. A common occurrence is for a trading firm to hit bids or lift offers in a dark pool and then do the same in the public markets with such speed and in such quantities that they move the price. Contra-parties in a dark pool could suffer an immediate loss from this type of behavior. Morgan Stanley focuses on a pattern of this behavior to maintain the integrity of MS POOL.
Certain types of activity are not healthy for our pool or our clients, Morgan Stanleys Johmann said.
Consistency is a key factor when judging the behavior of a particular participant, Morgan Stanley execs say. A trader that consistently provides good liquidity will score high in the firms monthly surveys. One that consistently provides bad liquidity will score low.
For firms in the business of providing liquidity, Morgan Stanley prefers them to make markets across several names and not just trade when they want to. We would prefer to see someone make a market in 100 names throughout the day, over someone who makes a market in one name and only trades in brief stretches of the day, Johmann said.
Barclays distills a traders activity into a modified take ratio. The stat is calculated by dividing the number of times a participant takes liquidity by the number of times he supplies it. In general, a higher score signifies a more opportunistic trader. A lower score signifies a more benign or good provider of liquidity.
The calculation is modified, meaning it is not one of simple division. The ratio takes into consideration such factors as the size of the order and the liquidity of the stock. Taking liquidity in a very liquid name like the QQQ, for instance, does not factor into the calculation as much as taking liquidity in an illiquid name.
The broker combines that ratio with a measure of market impact, or short-term alpha, to create a profile of the trader.
The short-term alpha variable is calculated by dividing the price at which the trader bought or sold stock into the price of the stock shortly after the trade. A positive short-term alpha suggests an opportunistic trader. A negative score suggests a more benign trader. That trader is less concerned about short-term profit and more interested in just getting the trade done.
It is only by weighing the two together that an accurate picture of behavior emerges.
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