Generally, the fees associated with short selling are margin interest charges, and stock borrowing fees.
Margin Interest: This is interest accumulated on any outstanding margin balances. You incur this charge when borrowing funds against your marginable securities to purchase additional securities or for cash withdrawals. Margin interest accrues daily and is billed monthly. You can find the most up-to-date margin rates within the schedule of fees.
Stock Borrowing Fee: This fee is for borrowing the stock needed to execute the short sale. It only applies to stocks with limited borrowing availability. Stock loan rates and borrowing availability fluctuate daily based on market conditions, and the fee is calculated and charged every day.
Fees for HTB stocks:
A hard-to-borrow stock is a stock that has limited shares available for short selling. For hard-to-borrow, or HTB stocks, there is a fee associated with shorting the position. The calculation for HTB fees is previous end-of-day stock price x 1.02 (rounded up to nearest dollar) x shares x rate /360. This is assuming the current convention rate of 1.02.