Accelerated Vesting

What Does Accelerated Vesting Mean?
A form of vesting that takes place at a faster rate than the initial vesting schedule in a company's stock option plan. This allows the option holder to receive the monetary benefit from the option much sooner. If a company decides to undertake accelerated vesting, then it may expense the costs associated with the stock options sooner.

Investopedia explains Accelerated Vesting
Prior to the adoption of FAS-123(R), U.S. companies were not required to account for stock option compensation paid to employees and executives. As a result of FAS-123(R), companies were required to account for stock option expenses, which amounted to a large expense for many companies. By adopting an accelerated vesting program, companies can expense their vesting costs over a longer period of time, which makes their future incomes higher than they would be if the options were vested on schedule.