An individual who assists buyers and sellers in trading is known as a:

A broker is defined as a person or entity that facilitates transactions between buyers and sellers, typically in financial markets. Brokers earn a commission or fee for their services and provide expertise, market access, and various insights to help clients make informed decisions. They do not take ownership of the assets they trade, acting purely as facilitators of transactions.

In contrast, a dealer typically buys and sells securities for their own account and can hold inventory, taking on risk directly associated with trade fluctuations. An auditor is responsible for examining financial records and ensuring compliance with regulations, which is unrelated to facilitating trades. An intermediary, while it may refer to someone who acts as a link between two parties, does not specifically pertain to the financial trade context where the role of assisting buyers and sellers is primarily defined as that of a broker. Therefore, the term "broker" precisely describes the role of assisting buyers and sellers in trading, making it the correct answer.