While the events that trigger the acceleration of vesting can vary by contract, there are a few common structures.

The first is called single trigger acceleration. In single trigger acceleration, the vesting is accelerated when a change of control (AKA acquisition) occurs. Investors, however, might find giving key managers single trigger acceleration disconcerting. What happens if the acquirer requires the key personnel to stick around through the post-acquisition transition? If these key managers get their payouts on the day the transaction occurs, they may not have an incentive to help out after the acquisition, a risk that can scare of likely acquirers.

As a result, managers that are likely to be key to the transition of the company after its acquisition are typically offered double trigger acceleration. This structure requires two events to take place in order for acceleration to be triggered. First, a change of control must take place. Second, the manager must either work for the acquirer for a pre-determined period or be dismissed by the acquirer. These managers still get their payout, but have an incentive to support the acquirer after the acquisition.

Double trigger acceleration is an important requirement as it can prevent the expectation of selfish behavior from derailing acquisitions.