Accelerated vesting is a form of vesting that occurs at a more rapid rate than the rate defined in the company’s initial stock option plan vesting schedule. Accelerated vesting allows for option holders to receive the monetary advantage from their option much sooner than previously defined by the initial vesting schedule. This usually is conditioned on some event, leading many to refer to the scenario as “single trigger acceleration” if there is one event that causes the acceleration.
Accelerated Vesting selection at Investopedia
Rob Fitzpatrick's Equity basics: vesting, cliffs, acceleration, and exits at The Startup Toolkit
Andy Rachleff's What You Need To Know About Vesting Stock at Wealthfront
What is Accelerated Vesting? at The Motley Fool
Startup Vesting & Acceleration at Priori Legal