Which of the following acts as an agent when filling orders for clients?

Brokers act as agents when filling orders for clients, which is a core function of their role in financial markets. Brokers facilitate transactions by executing buy or sell orders on behalf of clients. They do not hold inventory of securities but rather connect buyers and sellers to ensure that trades execute at the best possible terms for their clients. They charge a commission or fee for this service, which is how they generate revenue.

In contrast, dealers operate as principals in trades, buying and selling securities for their own accounts. They maintain an inventory of securities and may take on risk in the hope of profiting from market movements. Transfer agents are responsible for maintaining records of ownership for securities and handling transactions such as transfers and dividend payments, while custodians safeguard clients' assets but do not execute trades on behalf of clients. Understanding these distinctions is crucial for grasping the various roles within the financial markets.