There's a market, there's not a market of unlimited size (or even one large enough to make a meaningful difference to solvency). As one upper limit, if you borr

There's a market, there's not a market of unlimited size (or even one large enough to make a meaningful difference to solvency). As one upper limit, if you borrow literally every publicly available share and sell it short, that limits you to hedging bonds up to the total market capitalization of the company.