A slang expression that describes a situation where market prices are dropping rapidly. Stock market commentators may say: “The stock market is in the tank”, after a trading day that saw prices plummeting. Broadly speaking, an economy or an economic sector could also be in the tank when it performs very poorly. A security or market is said to be tanking if it is taking a downward trajectory. Investments that are going in the tank are not performing as expected. Likewise, a tanking investment position is one that is deteriorating or accumulating losses.

In general, anything that is said to be in the tank or tanking must be doing poorly for the time being.