noun
A person or firm that buys and sells stocks on behalf of clients. This is a formal, somewhat dated term; in modern contexts, 証券会社 (securities company) or ブローカー (broker) are more common.
彼は株式仲買人として長年働いてきた。
He has worked as a stockbroker for many years.
Compound of 株式 (stock) + 仲買人 (broker, middleman). The term reflects the traditional role of an intermediary in stock transactions.