My broker (IB) is showing two different rates for borrowing stock to short. I normally short cheap borrow stock so it never mattered much but now looking at expensive ones. One is the Current Rebate Rate. The other is the Current fee Rate. What is the difference? Say if Current Rebate Rate is -20%, and the Current Fee Rebate is 21%. What does the person pay? Is it just the 21% APR, or is it 20+21 = 41% APR in this example? And for how long does someone 'borrow' the shares in terms of how long interest is charged? Is it the time difference between settlements of opening and closing positions? Or is it from the day a position is entered in to the settlement (basically lengthens it a bit)?