Glossary
Margin Call
Trading
A margin call is a broker warning that account equity has fallen too close to the margin required to keep open positions.
Brokers set a margin-call level (commonly 100% margin level) and a stop-out level (commonly 50%). At the call level you can no longer open new trades and must add funds or reduce exposure; at the stop-out level the broker liquidates positions automatically, starting with the largest loser.
Margin calls are a symptom of oversized positions rather than bad luck. Sizing so that a full stop-loss costs 1-2% of equity makes stop-outs statistically very unlikely.