Here's
IBKR Margin Rate page, it can be used to calculate rates based upon account size, and Lite or Pro account.
IIRC, they base their interest rate on LIBOR, rather than the US benchmark that many other brokers use.
When I tried this tactic with Fidelity they were candid about not being able to come close, but, they did offer me a small rate adjustment. So, if you try this with E*TRADE, report back on how it goes.
I ended up transferring some shares to IBKR to get the rate, and kept the rest in Fidelity. I like Fidelity's interface better. IBKR is convoluted and it is like pulling teeth to master their reporting system in order to get basic stats about the shares, the account, etc. It leaves me with the feeling they have built their system to promote lots of trading on margin, using options, etc. and it can be clumsy and unintuitive for a long-term investor. Probably fine for the gamblers.
FWIW, this is working fine for using Margin the way I wanted. I just ignore their attempts to helpfully steer me toward the other stuff.