Auto square off is a feature that you will encounter when you are trading in Intraday. When you buy or sell a share and you forgot to close the trade before the end of the day, the stockbroker will automatically square off your trade to close the trade. This happens when you have taken an intraday position and forgot to close the intraday position before the end of the day.
The Auto square off timings vary for different brokers, usually, the Equity intraday positions are squared off between 3:10 – 3:25 PM based on the broker you have and also each broker changes these timings every time based on the volatility in the market.
This also happens when your position is going into loses and you have fewer funds available in your account. In such a case, your stockbroker will auto square off your position to prevent further loses from happening. This is basically part of the risk management system of brokers.