Born and raised in Cleveland, Ohio, in a Jewish family. After graduating high school, she attended Western Reserve University but left when her father got ill, without getting a degree. At 22, she began her career working for various brokerages, and after moving to NYC at 26, she worked as an analyst at several financial services companies.

In 1967, at the age of 39, she founded her own firm – Muriel Siebert & Co., Inc. In the same year, she applied for a seat on the NYSE but was declined with a request to secure $300,000 funding from a bank, but no bank would lend her the money until she is admitted at the NYSE. It did not stop her, and at the end of that year, her application was approved, and she became the first woman NYSE member.

Ten years later, she was named Superintendent of Banks for the state of New York – overseeing all the banks in the state. During the five years she served in this position, not a single bank failed. During the 1990s, her company merged with another company, which enabled them to liquidate and to become a publicly-traded company. After the merger, she remained president of her firm.

Siebert was a leading advocate for women and minorities in the banking and finance industry. She believed that undermining the contribution of women in government, business, and leading roles are putting the US at a disadvantage compared to other countries. She founded the “Siebert Entrepreneurial Philanthropic Plan,” in which she shared half of her company profits with charities of the issuer’s choice, offering them to help their community. Additionally, she served as president of the New York Women’s Agenda, in which she developed a program promoting financial literacy for women. Through the Muriel F. Siebert Foundation, she developed a financial literacy program for middle and high school students as well as adults, teaching them essential financial and business skills.