Most large caps are general collateral and cost well under 1% a year. Names with heavy short-interest and limited float can run to double or triple digits, and the rate can change daily without notice.
This is a carrying cost that compounds against a short the way time decay works against a long option: you need the move to happen soon enough to outrun the fee.
Example: short $100,000 of a stock at a 60% annual borrow rate. That is roughly $164 a day, about $4,900 a month. A 15% decline over three months earns $15,000 gross and roughly $500 in fees at general collateral rates — but nearly $14,800 at 60%, leaving almost nothing.
Related: hard-to-borrow, locate-requirement, short-interest, fully-paid-securities-lending