Final answer:
In a stock split, the company's transfer agent or its shareholder services department is responsible for maintaining shareholder records and distributing additional shares accordingly.
Step-by-step explanation:
In the event of a stock split, the party responsible for maintaining a record of the shareholders eligible to receive the additional shares is typically the company's transfer agent or the shareholder services department within the company. These entities ensure that the stock split is executed appropriately and that the correct proportion of new shares is distributed to existing shareholders based on their current holdings. The exact record-keeping can vary depending on whether the company uses a transfer agent or handles shareholder services internally.