The goal of the stock ban in F&O is to curb excessive speculation. When a stock's total open interest exceeds 95% of the market-wide position limit (MWPL), the stock exchange imposes an F&O ban. Traders are not allowed to open new positions in the stock that is subject to the F&O Ban during this time. But by squaring off positions, they can decrease their stake in that stock.
There is a chance that a stock may soon be added to the ban list if its MWPL is greater than 80%. A stock has a chance of leaving the ban list in the near future if its MWPL begins to fall below 95% while it is on the list.