What it is
Margin trading lets investors buy more stock than their cash allows by borrowing from the broker, paying interest and pledging the shares as collateral.
Maintenance
If falling prices push collateral below the broker's maintenance ratio (often around 140% in Korea), the investor must add cash or the broker sells the shares.
What to keep in mind
A surge in market-wide margin balances means lots of leveraged buying, and in a sell-off cascading forced sales can deepen the decline.
This explanation is general information, not investment advice. Rules reflect September 2026 and may change; check official exchange and broker notices.