Share split processing is the work that depositories, custodians, brokers and registrars carry out to give effect to a stock split, in which each existing share is divided into several. Because holders have no choice to make, it is a mandatory corporate action. The issuer announces the ratio, the record date and the effective date; intermediaries capture the event, notify holders and, on the effective date, the depository credits the extra shares or replaces the old line with a new one.
Each firm then repeats the change in client accounts and adjusts everything that refers to the old share count: prices and price history, open orders, unsettled trades, stock on loan, collateral and derivatives. Cost per share is reduced through a tax lot adjustment, leaving total cost unchanged. Uneven ratios can leave fractions, handled under the stated fractional share treatment. Positions are reconciled to the depository afterwards to confirm the new quantities.