What is a volatility interruption (VI)?

A VI is a mechanism that gives investors a cooling-off period by allowing only single-price auction trading for 2 minutes when the price of an individual stock temporarily changes sharply due to order errors, supply-demand imbalances and the like.

VIs are divided into dynamic VIs, which mitigate momentary sharp price changes, and static VIs, which mitigate cumulative, longer-term price movements. Being unable to trade immediately at the price you want while a VI is in effect is a market measure, not a failure of your securities firm's computer system.