My AUM is $5M, my Excess Liquidity is $2M, my new Exposure Fee would increase my lending rate from 50bp to 55bp, so there is no deal in town that cheap. .
It is not really a good deal (I assume you also see that). You cannot buy a house for it. You just that have a stable situation and then someone says 'lets pretend I have loaned you mlns more and charge you a fee for that'.
If you look at interest, IB has also started a trick with what they call blended rates. When you have an account with EUR 1 mln cash and a EUR 800k margin requirement, you would think the margin is covered by your cash.
However, with the blended rate idea, IB will pay you 0% interest on you cash balance, but let you pay 1.6% on the margin. So you will pay them interest even though you give them more cash than margin you need.