What term refers to leaving a security registered under the brokerage firm's name instead of the investor's?

The term that describes leaving a security registered under the brokerage firm's name rather than the investor's is known as "Street Name." When securities are held in street name, they are registered in the name of the brokerage firm, which simplifies the process of buying and selling shares for the investor. This arrangement allows easy transferability and quicker transactions since the brokerage holds the assets on behalf of the investor. Additionally, having securities in street name can provide convenience for the investor, as they receive a consolidated account statement and can easily execute trades without the need for physical certificates.

Other terms provided, such as Brokerage Registration, Custodial Name, and Investor Registration, do not accurately capture this specific practice within the context of securities and investments. Brokerage Registration typically refers to the overall registration of the brokerage as a licensed firm, Custodial Name implies a different arrangement where a custodian holds and manages assets, whereas Investor Registration would indicate the securities being directly registered in the name of the individual investor, which is not the case here.