front-month roll drags performance in contango.
UNG owns and rolls front-month futures, creating negative roll yield drag in contango — better suited for trading than clean delta-one exposure.
UNG's structural flaw is that it holds only front-month contracts; when the curve is in contango, the monthly roll systematically erodes returns. This makes UNG a poor vehicle for a buy-and-hold thesis and better reserved for short-term tactical trading.