The basis can develop a widening trend when the spot price of an asset/ commodity increases faster than the futures price. For example, CBOT November wheat futures are up 3 cents, while the wheat bid for March delivery is only up 1 cent. As such, the basis has widened 2 cents. In the same token, the basis can widen when the spot price bid decreases more than the futures price does.

A widening basis is the opposite of a narrowing basis.