Depends on which stock you want. If you want GameStop, it is Computershare. They als o handle some other stocks like apple. If you already own the stock thru a broker like Fidelity, they will transfer it for free, not all brokers do it for free.

You want the transfer agent for that particular stock,they will register it in your name.

Bbby is AST you can buy stock thru them or transfer you stock in from your broker. I have all my GME in computershare.

Transfer agent. Each stock uses their own. For GME it is ComputerShare., for example. You can instruct your broker to direct register your shares with the transfer agent.