Which transistor configuration has the lowest current gain?

The common-base configuration has the lowest current gain among the three basic transistor configurations (common-emitter, common-base, and common-collector). In this configuration, the current gain, often represented as α (alpha), is typically less than 1, as it is defined as the ratio of the output current to the input current. This results in lower overall amplification compared to the other configurations, where the common-emitter and common-collector setups provide higher current gains.