usually there are multiplier. i.e. FD & Cash is 2.5-3x multiple. Shares normally have 1.5x multiple.

for example, if you pledge 100k FD, you should have 250-300k buy limit. or if you pledge 100k shares, you should have 150k buy limit. I believe you can also mix & match collateral types.

calculation of margin calls are using total outstanding divided by total equity value. for force selling, you need to check with your remisier what is the pre-agreed conditions.

from my personal trading experience, Maybank & Cimb's margin would be the most competitive. while most remisier will tell you they can match the interest rate, they don't tell you the given value of the shares (lesser given value means lesser leverage) upfront or worst, once you've bought the share, they will tell you that the share aren't marginable and request for you to pay in full or sell the shares on T4. avoid Publicbank's margin at all cost!