What is the watch brand with the highest vertical integration?
Disclaimer 1: Not a discussion whether vertical integration is good or bad or makes sense or is historically "un-swiss" because the industry was historically horizontally structured.
Disclaimer 2: This is also not a discussion about whether stuff is made in a mode of production that is artisanal, manufacture or industrial.
By vertical integration I mean they develop the largest part of their production themselves, they then make it themselves - possibly down to the tooling and machines. They buy as little as possible from outside parties. They do not use movements developed or made by others, not even as a base for their own movements. Ideally, they also wouldn't sell any of their movements to others, so that their movements can only be had in watches with their brand on it.
To my knowledge Seiko and Rolex are probably closest to that. Perhaps Seiko ranks even higher than Rolex in that regard. I guess A. Lange also has a high degree of vertical integration. I think they only buy some of their balance and main springs from the outside. Their movements cannot be had in other watches and they are entirely original designs. However, the company was reportedly resuscitated with a lot of know-how from JLC. Totally OK in my book. The know how has to come from somewhere. Might as well take the best.
How vertically integrated is Patek for example? And JLC?
We know that Patek, AP and VC have all used JLC calibers. We also know that AP and VC also use Piguet calibers. Does Patek still use any JLC?
We also know that some bracelets and cases even by the big names are not done in-house but by first class suppliers. Again, not a question of quality but a question of degree of vertical integration I am asking.