A jobber, also known as a market maker or dealer, is a type of trader who actively buys and sells financial instruments, such as stocks, bonds, and derivatives, in order to facilitate trading and provide liquidity to the market. Jobbers typically work for large financial institutions, such as banks or brokerages, and their primary role is to bridge the gap between buyers and sellers by continuously quoting prices for financial instruments and executing trades on behalf of their clients. Jobbers are an important part of the financial markets as they help to ensure that buyers and sellers can find each other and trade smoothly, which helps to maintain market efficiency and stability.

In trading, a jobber is a term historically used in stock markets, particularly in the London Stock Exchange, to describe a market maker or dealer who buys and sells securities to provide liquidity. Jobbers operated by quoting two prices: the bid price (buying price) and the offer price (selling price), profiting from the spread between them. Unlike brokers, who acted as agents for clients, jobbers traded on their account, ensuring smooth market operations.

The role of jobbers diminished with the rise of electronic trading, which automated market-making functions. Today, similar roles are performed by market makers or liquidity providers in modern exchanges. Jobbers were crucial in maintaining orderly markets before digital trading took over.