It even seems to skirt around notions of illegal vertical integration. For example in this address from 1998, a former FTC commissioner describes several types of illegal "vertical alliances", all of which rely on both the upstream supplier and the downstream consumer being aligned in anticompetitive intent, which (if the article is to be believed) they couldn't have been here because there are two suppliers who were unaware of each other's deals.
Is it really not illegal to just buy up a huge chunk of a critical input for an industry and stockpile it for the purpose of locking out competitors? Seems hard to imagine that some robber baron of the 19th century didn't already do this.
They tried it and lost their shirts. When you hoard a critical input, that input doesn't just disappear. You spend huge amounts of money pushing the price up, and then the market price turns against you as people finally figure out that the hoarding was just a stunt, that you don't really have a higher-valued use for the stuff you hoarded, and all of it is going to be right back on the market sooner or later.
and here's a followup from the same commissioner https://www.ftc.gov/news-events/news/speeches/vertical-issue...