The causes of losses or margin calls in forex trading can vary but typically stem from a lack of risk management or trading discipline. Overleveraging, ignoring stop-loss orders, and emotional trading can all lead to significant losses. Trading without a well-defined strategy or failing to analyze market trends and news can also result in costly mistakes. Additionally, unforeseen events such as unexpected market volatility, geopolitical tensions, or natural disasters can trigger margin calls. Proper risk management and a disciplined approach to trading can help minimize the risk of margin calls and mitigate potential losses.