Yeah, quite impressive language to make the backbone of all your systems.

I doubt that it is used for actual trading. Maybe the OP can elaborate what the live infrastructure and backtesting setup look like?

> I doubt that it is used for actual trading.

Do you have a basis for that claim?

JS have developed tons of libraries and tools for OCaml development, and new developers and quants that they hire go through an OCaml bootcamp to come up to speed. They put lots of work into the OCaml compiler, and in blog posts about that work they talk about why this is useful for trading. Maybe I'm missing something crucial, but I think it's more likely that you just don't know what you're talking about.

Of course they use it for trading and everything around for many years.

they use it for the control plane. it's clearly not used for actually submitting trades.

Do you mean this tool, or OCaml? They are definitely writing their actual trading systems in OCaml, they have been publicizing this for many years.

that is what i thought. the actual trading code is probably in c or c++ or is in an fpga being controlled by the trading code.

cool, so how about the OP shares the details of how they use it for trading?

That's largely what their excellent Signals & Threads podcast is about.

https://signalsandthreads.com/

> Listen in on Jane Street’s Ron Minsky as he has conversations with engineers working on everything from clock synchronization to reliable multicast, build systems to reconfigurable hardware. Get a peek at how Jane Street approaches problems, and how those ideas relate to tech more broadly.

I think just the idea of a company that does not directly produce things, and instead spends its efforts turning its money into more money via investment, is something that... doesn't entirely sit well with me.

There is, of course, something to be said about the by-products of their work. Jane Street is far from an evil company, and I would not be entirely morally opposed to working for or with them. They do a lot of good in academic research in areas I care about. I just wish that that was their primary purpose instead of direct money-making, if that makes sense.

Fwiw, market makers sometimes say that by providing liquidity they benefit the whole market.

Doesn't that pretty much characterise all for-profit companies?

I think for a lot of people there's a pretty big difference between these two business models:

- We use cash to buy circuit boards, screens, enclosures, etc, write software, and sell mobile phones.

- We use cash to rent a building, order pallets of inventory, and sell that inventory locally to walk-in customers.

- We use cash to buy shares, hold onto them for a bit, and sell those same shares and make money off the spread.

I'm not making any kind of comment at all about the value of market makers, just... those three businesses feel like they're different models.

They are the same model. They both buy stuff, do some stuff and then re-sell the same stuff but with the modifications they made.

In the case of a trading shop, the stuff they do is playing the market liquidity, collecting interest, arbitrage, etc...

Sure there are some evil ones, but other businesses have those too.

Yes, this is pretty much it. As I said in another comment, Jane Street does not have customers for whom they provide goods or services. Their primary business model is using the company's own money for investments, and that's a business model that I don't love.

Considering how many high finance shops live off of gambling with other peoples' money, I find the intellectual honesty of a company doing it on their own dime ... refreshing.

Company spends its own money to make money for itself?

Not exploiting teenagers in some 3rd world country?

Not gambling with your pension?

Not manipulating some physical commodity like oil?

What’s the problem here?

> Not exploiting teenagers in some 3rd world country?

> Not gambling with your pension?

> Not manipulating some physical commodity like oil?

There is no reason to believe #1 and #3 aren't true, and I should very much suspect they are. #2 is not possible as far as I can tell, I agree there.

> - We use cash to rent a building, order pallets of inventory, and sell that inventory locally to walk-in customers.

> - We use cash to buy shares, hold onto them for a bit, and sell those same shares and make money off the spread.

Those two sound like pretty much the same thing.

Indeed, but not like the first one.

Does that cover the entire financial industry?

Not necessarily. Companies that facilitate trades (eg, E-Trade) don't fall in this category, because their business model is about providing a service to regular people.

Jane Street is a proprietary trading firm. They have no external customers to whom they would provide goods or services. Their primary purpose is to invest the company's own money.

I think an economist would say market makers reduce the volatility of a market, which does benefit regular people.

You think they are platinum-level sponsors at multiple conferences every year, sponsors of PLMW multiple times a year, sponsors for carbon-neutrality at ICFP each year, and continue investing in hiring PhDs and improving the OCaml ecosystem because... the... cost of switching away from OCaml is too great?

I don't think that tracks. They like OCaml, and they are pretty adamant that it is a good tool for the job. Maybe you disagree, but you should not project your opinions on them.

I bet it is also a great way for them to hire and retain great engineers, including the kind that isn't just in it for the money.

Speaking only of what I see (I'm a PhD student in the field of programming languages), quite a few people seek internships and full-time employment with JS specifically because of the tech stack and the kind of problems they (JS) tend to like throwing themselves at. They do some seriously cool stuff, and they've published a lot of great research!

I don't think that's the situation, but if you are irreversibly committed to a technology, you have an interest in seeing that tech continue to advance. Being stuck on a dead tech is even worse.

> I don't think that's the situation

I'm not sure what you mean by this. What is the situation?

> Being stuck on a dead tech is even worse.

Why do you think OCaml is a "dead tech"? Can you justify that? Or is it just based on the notion that if most people don't use it, it must be a bad tool?

I dont think he's saying it's dead tech. He's saying their incentive to invest into ocaml is to make sure it doesn't become dead tech.

Pretty much yes.

Cost is more than just monetary. There are significant indirect costs as well.

> There are significant indirect costs as well.

Can you elaborate on these costs? Do you have knowledge of JS's internal needs and resources to suggest a better alternative?

They are not just hapless consumers of a dead language; they actively maintain it and invest in it because it works well for them. The language itself gives them the kind of guarantees they want in their work, and their work on the language and surrounding tooling (among other things) helps them to acquire high-skill talent. I don't know how you can claim that they would transition to another language if they could without having some pretty firm data to back that claim up. Otherwise, I think you're just projecting your own feelings about OCaml onto them.

You seem eerily passionate about JS all over this thread.

Nowhere did I mention that Ocaml was a dead language or a dying language. I simply stated that there are insurmountable switching costs which incentivizes them to contribute to the larger Ocaml community.

I think they are mostly here to hire people. Not to educate.

If by "here" you mean "at academic conferences", then I'd ask you why they bother to actually do primary research and publish it if they have no interest in sharing knowledge.

If all they wanted was to hire people, they... would. You don't have to sponsor a conference to attend or hire from that conference. And you especially also don't need to sponsor additional workshops, or carbon neutrality initiatives, or anything else.

It's genuinely silly to suggest that they spend all this money on things just to hire people. There are so many more effective uses of their money if that is the only goal.

because they are hoping to run into interesting people to hire. why would they share knowledge otherwise? if they are interested in doing that, why not share all the details of their tech stack and what they are doing exactly in the market? it's very hard to hire, especially with FAANGs who compete with them for talent.

> why would they share knowledge otherwise?

Because they believe in the value of science?

They don't need to publish to compete with top-tier public companies. I don't know of any other trading firm that contributes to open-source development, or to a language infrastructure, or to academic advancement in the way and to the extent that Jane Street do. Most companies keep everything proprietary and highly secret.

But JS chooses to publish. And it's not like that's an easy task that you can just do for fun on a whim; it takes a long time to put together a good paper. They also regularly collaborate with people in academia on long-term projects and evaluations.

I understand the perspective you're suggesting, but I genuinely believe it is wrong, and I also believe that you do not have any evidence to back it up. I think their public contributions speak for themselves, but I've also met some of their more academically inclined engineers (including their CTO), and they come from an academic background and seem to genuinely believe in academic publishing as a goal in itself. It's not totally crazy that there exists one such company out there. (There are actually a couple, but not terribly many, and the others are not relevant in the present discussion.)