what is criteria for stocks on which zerodha provides margin, and do the list gets updated often,some have 3x and some have 11x margin, how is it calculated
The leverage criteria is based on the liquidity of the stocks.
Stocks with 11x leverage are the ones called FnO stocks which are also Futures and Options contract derivatives.
Stocks with 3x leverage are less liquid compared to the ones with high leverage.
11x leverage are for day-traders who mostly buy and sell FnO stocks.
Changes to the leverage list does not happen very often.