Survup, I do not know the answer to your question without knowing more specifics of your question (which timeframe).  However, anyone trading futures-based ETFs and especially natural gas ones, should be aware of the method they "roll over", when they "roll over", and whether and how much contango or backwardation is present.  The rollover date for UNG in February was Feb. 12-18, and for March will be March 13-18.  You may also want to understand how this roll occurs by searching a comparison of the UNG versus UNL ETFs.  Also, with natural gas, it is now in the rarer situation of being in backwardation instead of contango.  This implies that during the March roll-over, UNG should be prone to increasing versus the spot natural gas price instead of decreasing as it usually does when in contango.  Just my humble opinion, do your own research on this.