The third one was definitely the least, it was losing money (and specifically to trader-invisible things that never got worked on).

The whole of the trading strategy (and capital traded, return profiles, etc) between the first two was fairly different, so it’s hard to compare.

I would say though that the first firm was significantly outperforming its peers in a way the second firm did not, although both were very successful.

The technology wasn’t the whole story in either case, but the first firm had significantly more and better opportunities as a result of just having a better stack all around

It's generally pretty rare for a market maker to lose money over a whole year. Colour me surprised.

There's costs that aren't the PnL of buy-low-sell-high. The coders, the data, the infra. All cost money, a lot of money. Add to that there's a competitive aspect in the models interacting with each other, there's no slam-dunk.

There's at least a couple of MMs struggling these days.

True but I feel that the market maker label gets applied pretty loosely nowadays, couldve been a firm that mixes in a lot of intraday position taking trades that blew up