Introduction: In line with the globalization of the world financial market, in this project document, the issue of the functions of securities companies and investment banks in Saudi Arabia and in the functions of securities companies and investment banks in the United States of America will be discussed in detail. Definition of Investment Bank: An investment bank may be referred to as an organization or institution founded and united for purposes that specifically involve tax matters. They also act as an assistant in a subordinate or support function for a large company or group of companies, recognized by law and acting as a single entity, and the organization which is the governing authority of a political unity in increasing the quantity or value of its assets. by securing financial support and acting as a broker in the issuance of bonds. In accordance with this, an investment bank can be classified as a financial institution that fulfills the role of an investment bank, thereby carrying out or carrying out the activities of other operations related to finance, as well as asset management, stock research and many more. Additionally, the entire financial institution may be just one part of a larger financial institution such as a commercial bank. Therefore, an investment bank does not undertake the normal banking operations of depositing money unlike its peer banks in the category of retail banks and commercial banks. However, they assist in merging, contracting, taking over or acquiring possession of businesses. Additionally, investment banks offer support services such as market ordering and trading a financial instrument whose value is based on another security,...... middle of paper ... ...n Stanley, Salomon Brothers and Goldman Sachs. In conclusion, it will be found out that the role or functions of the financial institution of the Kingdom of Saudi Arabia are almost different from those of the United States of America as the functions are performed or performed by different financial institutions unlike to Saudi Arabia where SAMA, which is the central bank of Saudi Arabia, has the function of supervising the performance or operation of commercial banks and all other banking operations in the country, in the United States, institutions Financials are a division of commercial banking extended and advises companies on mergers and acquisitions, initial public offerings (IPOs), debt underwriting and leveraged buyouts (LBOs), hence the hypothesis of the institution as a “corporate finance” or “consulting services” institution ».