qll, IB's margin rates are clearly defined in its website. What is the specific question that you have in mind? (Just2trade matches any margin rates that you are currently getting.)
IB's margin rate, charged for dollar balances over $3M, is currently 5.649%, substantially lower than the figure you gave. The figure you gave, 5.899%, only applies to those funds between the $1M and $3M tiers.
I think that if you are borrowing 500K in margin, then IB, currently, charges you 6.899% on the first 100K, and then 6.399% on the remaining 400K. So your total interest rate would be 6.899% * 1/5 + 6.399% * 4/5 = 6.499%.
Calculating the first 4 tiers at J2T the rate on $500K is 6.975%. Rate Loan Annual Simple Interest 6.75% $250000 $16875 7.00% $150000 $10500 7.25% $50000 $3625 7.75% $50000 $3875 Total $500000 $34875 6.975%
So IB is the clear winner, charging substantially less margin interest, no matter how much money is involved. This is based on your numbers, plus the 5th tier for J2T being 6%, as claimed previously in this thread.
qll, for the retail brokerage firms who offer per share pricing, as far as I now, IB has the lowest margin rates for the long positions. Just2trade margin rate can be as low as IB's--if not lower at times--because it claims to match margin rates provided you send them the last 2 monthly statements; however, it does not offer per share pricing. You should also ask your broker(s), how often do they deduct margin charges out of your account. If they do it daily rather than once monthly, then it may actually cost you more.
harry11, suppose broker-A takes away $100 everyday for 30 days as margin charges for long positions from your account. On the other hand, suppose broker-B takes away $3000 on the 30th day as margin charges for long positions from your account. They both may take away the same amount of money, but you will more buying power till day-29 with broker-B. This is just one example.