I am skeptical of your explanation of short stock interest. Although I don't use margin so I could be wrong.Quote from exQQQQseme:
Interest Calculation on Shorted Stocks:
8 Ball and Others, I had promised an explanation of how the margin interest is charged when stocks are shorted. Actually, AAPL's $6 rise yesterday made this explanation quite simple. Look at my posting immediately prior to this one (page 15), where I use AAPL. It is a perfect example.
Assume the broker charges 8.5% annual interest. The interest is charged on a daily basis and is collected monthly. Thus, the $1,000 margin debt in that example is subject to a margin interest charge for the day. The computation would thus be:
$1,000 x .085 / 360 = 24 cents for the day.
On this point I speak from actual experience. This is not theoretical conjecture. Also, what is interesting is that if by chance one also had shorted puts in their account, the premium received would have been part of the $5,000 starting balance, but the short value of the put would NOT be part of the $1,000 margin debt amount. This is a nice, but small, added benefit which surprised me a few years ago when I first became aware of this.
Can anyone else confirm 4Q's explanations?
P.S. My understanding is that if you fall below margin requirements you must deposit more cash or liquidate. I never heard that the broker simply charges interest on your shortfall.