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.