Some thoughts on how big market making firms (eg Jane Street, Susquehanna, Optiver) are structured. Note I have not worked at any of these firms so this is not based on any insider knowledge, just talking to people in the industry and extrapolating a bit.

A “pure” market making operation is based on clipping spreads, ie buy low, sell high, keep inventory low, keep risks (eg greeks) tightly hedged. Skew your bid/offer based on your inventory to try and offload it as quickly as possible without impacting your profit too much.
This kind of trading has enormous risk-adjusted returns (Sharpe > 10, ~no down days) but it’s hard to scale it because your P&L is a function of two things — volume and volatility — that you don’t have any control over.
This is a problem because the costs of running a pure MM firm (mainly infrastructure and employee comp) are increasing and profit margins are decreasing. So many firms turn to prop trading as a way to increase P&L at the cost of some Sharpe.
One way to approach this is to make your price skew dependent on factors other than your inventory, eg if you think the market is going up you skew prices a little higher to encourage people to sell to you and discourage them from buying from you.
(To some extent even pure MM firms do this since they use very short term signals based on the order book in addition to their inventory to skew prices, but I’m talking about adding longer term signals using a wider variety of input data.)
This also becomes hard to scale after a while because it relies on having a centralised book which has a view on everything, this creates coordination problems and increases risk of IP leakage as many more people can see the whole system.
So the approach that many places gravitate towards is having a central market making book (just using inventory and simple signals to skew prices) and satellite prop books which exist purely to trade with the firm’s capital. These prop books can trade with the MM book
under some agreement, generally very favourable pricing if they are taking risk off the central book and less favourable if they are adding risk. These books can be run be completely independent teams which reduces coordination problems and IP leakage risk.
Now whenever a prop book thinks the price is going up they buy from the MM book which leaves the MM book short, they therefore skew their prices up to encourage others to buy from them and cover the short. The prop book alpha is transmitted to the MM book.
This simple but elegant mechanism solves many of the scaling problems inherent in running a MM firm. It is also why it is a mistake to think that you can “run over” a big market maker by trading heavily in one direction with them — they are capable of leaning
against or following your flow in their prop books depending on where they think the market is going. Fin.

More from Trading

Many of you have seen the famous Westrum Organizational Typology model, so prominently featured in State of DevOps Research, Accelerate, DevOps Handbook, etc.

This model was created Dr. Ron Westrum, a widely-cited sociologist who studied the impact of culture on safety


Thanks to Dr. @nicolefv, I was able to interview him for an upcoming episode of the Idealcast! 🤯

It was a very heady experience, and while preparing to interview him, I was startled to discover how much work he's done in healthcare, aviation, spaceflight, but also innovation.

I've read 4+ of his papers, so I thought I was familiar with his work. (Here's one paper:
https://t.co/7X00O67VgS)

I was startled to learn he has also studied in depth what enables innovation. He wrote a wonderful book "Sidewinder: Creative Missile Development at China Lake"


Dr. Westrum writes about China Lake Research Labs: "its design and structure had one purpose: to foster technical creativity. It did; China Lake operated far outside the normal envelope... Sidewinder & others were "impossible" accomplishments,

I love this book because it describes traits of organizations that routinely create and maintain greatness: US space program (Mercury, Gemini, Apollo), US Naval Reactors, Toyota, Team of Teams, Tesla, the tech giants (Amazon, Google, Netflix, Google)

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The chorus of this song uses the shlokas taken from Sundarkand of Ramayana.

It is a series of Sanskrit shlokas recited by Jambavant to Hanuman to remind Him of his true potential.

1. धीवर प्रसार शौर्य भरा: The brave persevering one, your bravery is taking you forward.


2. उतसारा स्थिरा घम्भीरा: The one who is leaping higher and higher, who is firm and stable and seriously determined.

3. ुग्रामा असामा शौर्या भावा: He is strong, and without an equal in the ability/mentality to fight

4. रौद्रमा नवा भीतिर्मा: His anger will cause new fears in his foes.

5.विजिटरीपुरु धीरधारा, कलोथरा शिखरा कठोरा: This is a complex expression seen only in Indic language poetry. The poet is stating that Shivudu is experiencing the intensity of climbing a tough peak, and likening

it to the feeling in a hard battle, when you see your enemy defeated, and blood flowing like a rivulet. This is classical Veera rasa.

6.कुलकु थारथिलीथा गम्भीरा, जाया विराट वीरा: His rough body itself is like a sharp weapon (because he is determined to win). Hail this complete

hero of the world.

7.विलयगागनथाला भिकारा, गरज्जद्धरा गारा: The hero is destructive in the air/sky as well (because he can leap at an enemy from a great height). He can defeat the enemy (simply) with his fearsome roar of war.