Have you ever encountered this problem? $ETH Why did I open a short on BTC at 70,000 with 100x leverage and 1,000u margin, but after a 10% drop, my margin became 900u? $M Would all subsequent P&L be calculated based on 900u? Actually, no. This is an illusion. Let me first explain how P&L is calculated. $LAB At the moment of opening: BTC position size is permanently locked. Real-time P&L (U) = (Entry price - Current price) × BTC position size. After opening, you have a fixed short position of approximately 1.4286 BTC. So how is that quantity calculated? BTC quantity = Margin × Leverage ÷ Entry price. Take 1,000u margin and 100x as an example, corresponding to a position size of 10wu. 100,000 ÷ 70,000 ≈ 1.4286 BTC short. Now, why has the position value become 900u? Margin = Notional value of position / Leverage. In other words, the margin displayed here is just calculated based on the current BTC price. If the price returns to the original price, it will go back to 1,000u. Summary: Real-time P&L is calculated based on BTC quantity and price change, unrelated to anything else. The position value is just displayed based on the real-time BTC price. You don't need to worry about that number; just look at your BTC position quantity. Follow Brother Jia, no bragging, no empty promises, only sharing practical experience that will let you survive in the crypto space. If you keep losing and restarting repeatedly, come talk to me, and I'll teach you how to make trading simple.