[cryptonector]

> antitrust is really simple in my view: companies should principally be in one line of business[0] as that's the most efficient configuration for the economy as a whole. some of those businesses will be larger than others as a natural consequence of the given industry (e.g., capital-intensive businesses like aerospace), but no business should be larger than it needs to be (in the long-term; short-term dynamism is "inefficient" but promotes longer-term optimality).

Would this limit vertical integration? E.g., could SpaceX exist under your scheme, making rocket engines, rockets, and satellites? Is that all one line of business, or is it multiple lines of business? Is Apple's hardware and software business one line of business or two (hardware, and separately software)?

It seems to me that your approach is easier to apply when a company strays from its line of business rather than vertically integrates. So a company that makes hardware, then years later gets into software for its hardware, that might be a problem, but then how could that be a problem if Apple-like companies exist concurrently.

I think all antitrust schemes are tricky and slippery. Not that we shouldn't have an antitrust scheme, but that I'm not sure how to construct one that doesn't somehow suck.

[clairity]

spacex, as far as i can tell, is a research company that launches satellites to fuel its space exploration research. the research side couldn't stand alone, as that's not a viable business in itself, so the satellite business is really the core "business" here. the making of rocket engines could possibly be outsourced (or turned into a separate business), but those customized engines are integral to its competitive advantage in more efficiently sending satellites into space than its competitors (and in sending people to colonize mars, its long-term mission). core competencies like that aren't separate businesses; they're the business itself. if spacex decided to write its own accounting software and then sell it to others, then you'd have a breach of the single business focus.

apple, however, is in something like a dozen different businesses that are completely viable as stand-alone entities that don't gain much from being consolidated (brand value, for instance, can be franchised if a unified brand face is desired, like mcdonald's does). incidentally, apple wasn't a hardware company that morphed into software, but rather, it was always a computer marketing business (then more broadly consumer electronics, and now encroaching upon consumer entertainment). nest is a good example of what a spin-out company in an apple breakup might look like.