A period during which stock is held after acquisition, whether through a purchase, an option exercise, a vesting, or a grant. The holding period starts on the day after the date of stock acquisition. The length of the holding period can significantly affect the taxation and securities-law requirements for stock acquired through equity compensation or on the open market and for restricted securities. For examples showing the importance of holding periods, see the glossary entries on ESPP disqualifying dispositions, capital gains, and Rule 144.