Separation of ownership from management. Tradeable claims on the firm. Legal personhood of the firm. Private property. Free trade between countries. Market determined prices.
But it’s lazy and wrong to use it as a synonym for greed. Despite Gordon Gecko, greed is not good. Just seeing something we consider bad and saying “Capitalism” is a pose and not an argument.
It doesnt forbid but it strongly inhibits. A system under which you are able to acquire vast resources then creates the ability to use those vast resources to sway the political process in your favor.
Even when the regulations exist (e.g. antitrust) regulatory capture will inhibit their enforcement.
It's surprising how many people consider this process to be somehow irrelevant or out of scope when you analyze how capitalism functions. It's a core feature.
Communism: https://en.wikipedia.org/wiki/Lake_Karachay
Totalitarianism: There were several regulatory oversight failures in Germany during their stint with Fascism
Capitalism doesn't forbid sensible regulation, it just hasn't happened as politicians don't really understand the space.
China, which runs a completely different economic system has similar issues.