What It Means
MIS (Margin Intraday Square-off) is a product type for intraday-only trades — your broker gives you extra leverage in exchange for a promise that the position closes the same day, either by you or automatically by the broker if you don't.
How It Works
Because the broker assumes zero overnight risk on an MIS position, it blocks far less margin than a delivery (CNC) or carry-forward (NRML) order would need for the same quantity. If you haven't closed the position yourself by the broker's cut-off — typically a few minutes before the 3:30 PM market close, though the exact time varies by broker and segment — the broker's square-off system closes it for you at the prevailing market price.
Example
You buy 100 shares of a ₹500 stock under MIS with 5x leverage: only about ₹10,000 gets blocked instead of the full ₹50,000. If you forget to exit and the auto square-off kicks in during a volatile last few minutes, you could get filled well away from the price you wanted.
Warning
Auto square-off isn't a safety net — it fills at whatever price the market gives in that moment, and some brokers charge a separate auto square-off fee on top of it.