[Rury]

Does it matter if they only own a small fraction of the homes? There's some studies that show that in markets where institutional investors do buy, prices typically noticeably increase for houses afterwards, even if they only own a tiny fraction of the housing units.

There's plausible argument as to network effects (e.g. my neighbor is charging that much, so why can't I?), as well as changing unit types to rentals, limiting owner-occupied supply and hence driving up prices.

I mean, I imagine it can be kind of similar in the stock market, where that you don't actually need to buy all a company's shares in existence to bid up a stock's price... you only need to buy enough of the available float to raise prices (sometimes which can be <0.5% of shares in existence).