Upside down, as the name implies, upside down. At present, it generally means that the actual situation of some social phenomena does not conform to common sense and violates the way it should be. Generally speaking, the futures price should be higher than the spot price, which is commonly known as "futures premium" because it includes inventory cost and capital cost; Only when the market atmosphere is extremely pessimistic and commodities are bearish for a long time, the futures price will be lower than the spot price, or it will be called "spot premium". This is the so-called term inversion, which should belong to a special phenomenon. Now the economic crisis in 2008 has shown this phenomenon in non-ferrous metal futures.