According to, Investopedia, as more shares are shorted, the total supply of lendable shares is decreased since fewer shares are available to borrow.
But the same shares that have been shorted can apparently be borrowed & shorted again according to (Can a single share of stock be shorted multiple times?) -- which seems to contradict the shrinking supply reasoning. Isn't this a theoretically infinite supply since there is apparently no limit?
How is the borrow rate influenced by the supply of lendable shares decreasing as short interest rises if there's nothing to prevent already shorted shares from being lent over & over again?