Leonard Leiman, a director at the Siebert Financial Corp., said on Sunday that Muriel "Mickie" Siebert had died of complications from cancer.

With partnerships at two leading brokerage firms and being the founder and president of Muriel Siebert & Co. Inc., Siebert attempted to get a seat on the then all-male exchange. However, this attempt was met with ridicule from much of its membership, as stated in her official biography found on her company website. Siebert eventually prevailed and took a seat as the first woman ever on the exchange in 1967. The next woman to accomplish such a feat would come almost ten years later.

Siebert's boldness did not end with her taking a seat on the exchange. In 1975, on the very first day that New York Stock Exchange members were allowed to negotiate their commissions, she transformed her firm into a discount brokerage.

In 1982, Siebert also made an unsuccessful run for the Senate, championing the cause of women and minorities. She lost to Republican primary Florence Sullivan.