Risk controls at machine speed

Graduate · enrolled learners

This lesson opens with Latour Trading, 2015.

What happened

Latour Trading was a high-frequency trading firm that made markets in stocks at machine speed, and it agreed to pay 16 million dollars, the largest penalty of its kind at the time, to settle SEC charges that it had violated the net capital rule. The rule requires a firm to hold enough capital against the risk of its positions, but for a period Latour used a flawed method to calculate that risk, understating it, so it operated with far less capital than the volume and risk of its market making actually required. Nothing dramatic announced the problem; the firm traded enormous size continuously, and a control that was quietly wrong, the calculation of how much capital its risk demanded, let it run far beyond what it could safely support without anyone seeing the gap in real time. A market maker takes on risk at machine speed, so the controls that measure and limit that risk have to be correct and automatic, because when they are wrong the firm accumulates exposure faster than a human could ever notice, and the miscalculation is discovered only after the risk has been carried for a long time.

The decision point

A market maker that trades at machine speed accumulates risk at machine speed, so the controls that measure and limit that risk, capital, position, and loss limits, must themselves be correct and automatic, because a control that is wrong or absent lets exposure build faster than any human could watch, invisibly, until it is discovered. Latour Trading is the case: an HFT market maker used a flawed calculation of the capital its risk required, understating it, and ran far more risk than it could support until the SEC caught it, at a 16 million dollar cost. This closes the market-making course on the theme running through it: market making is a risk business, and at machine speed the risk is only as controlled as the automated systems measuring it, so a firm whose control is quietly wrong is not safe merely because nothing has gone wrong yet. The danger of a bad control at machine speed is that it fails silently: the firm keeps trading, the exposure keeps growing, and because the control that should raise the alarm is the very thing that is broken, there is no alarm, only a gap that widens until an outside check finds it. So the discipline is to treat the risk and capital controls of a fast market maker as critical systems in their own right, to verify that they correctly measure the risk being taken rather than assume they do, to make them automatic because human oversight cannot keep pace with machine-speed accumulation, and to have them independently checked, because Latour shows that a market maker can run for a long time on a control that is wrong, carrying risk it cannot support, precisely because the broken control is the one that was supposed to say so.

Recorded loss

$16,000,000

Orientation and Year One are open: anyone can read them without an account. From Year Two onward the lessons are for enrolled learners, because progress through the later years only means anything if it is tracked against a record.

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