Margin Call Rally "One factor that may turn the market is something that is seldom discussed by analysts. This is the futures exchange margin. Traders should watch the natural gas futures markets for signs of increased volatility. Futures exchanges like the New York Mercantile Exchange (NYMEX) don’t like volatility especially if it hurts small traders. In order to rid the market of excessive volatility it often raises margin requirements, or the amount of money needed to hold a futures contract overnight.
If natural gas futures begin to have volatile price swings then look for the NYMEX to raise margins. This will increase the cost to hold short positions, forcing many undercapitalized traders out of the market and potentially driving prices sharply higher. This is a wildcard but traders should be aware of this because unexpected changes often turn markets."
source: oilprice.com