The ex-dividend date represents the specific cut-off trading day established by public stock exchanges and corporate boards, determining which registered shareholders are legally entitled to receive an upcoming dividend payout. To be eligible for the distribution, an investor must purchase or own the common stock shares before the ex-dividend date. If an equity is bought on or after this designated day, the previous owner retains the right to collect the declared dividend payment, causing share prices on the open market to typically adjust downward by an amount roughly equivalent to the payout value when trading opens.