The sudden drop that NG experiences in the first few hours of trading are primarily algorithmic trades & hedge funds closing out positions. Keep in mind-some algo's hold a position for less than 10 seconds. While their hold time is brief-the size of their positions is huge causing the immense volatility we see in many commodities (not just nat gas). The algos do also trade stocks but the volatility and regulation is higher when trading stock of a company. Sooner or later the algos will start moving Bitcoin-hence why I will absolutely not touch Bitcoin.
I have been taught to never trade before 11AM-eastern or 30 Minutes before market close. These are the highest points of volatility.