Muriel Siebert, whose success as one of Wall Street’s early, influential female analysts earned her the contacts and nest egg to become the first woman to buy a seat on the New York Stock Exchange, has died. She was 80.

She died on Aug. 24 at Memorial Sloan-Kettering Cancer Center in Manhattan, according to a statement from Siebert Financial Corp., which she founded and led. The cause was complications from cancer.

In paying $445,000 for one of the NYSE’s 1,366 memberships on Dec. 28, 1967, “Mickie” Siebert broke up the all-male bastion of the Big Board, which until then had permitted women on the trading floor only as clerks and pages to fill shortages during World War II and the Korean War.

The lack of enthusiasm for welcoming a female colleague was evident, Siebert said, in her search for the two sponsors she needed under membership rules. After several rejections, she got James O’Brien, a partner at Salomon Brothers & Hutzler, and Kenneth Ward, a partner at Hayden Stone & Co., to back her.

Much of the opposition was couched as kindness.

“There was all manner of concern for my delicate ears -- with several articles postulating that a woman couldn’t handle the rough language of Wall Street -- and many comments about the absence of a ladies’ room on the Stock Exchange floor,” Siebert recalled in her 2002 memoir, “Changing the Rules: Adventures of a Wall Street Maverick,” written with Aimee Lee Ball.

“Not since I was a baby had so many people been so interested in my bathroom habits,” she wrote.

Siebert’s revolution was at least partly symbolic, since she did most of her work away from the floor, researching companies and advising clients of her sole-proprietor firm.

Her stock-exchange membership meant that she could, when she desired, handle the actual buying and selling of securities, giving her a larger share of commissions.

Of the 62 traders, brokers and investors profiled by Martin Mayer and photographed by Cornell Capa for the 1969 book, “New Breed on Wall Street,” Siebert was the only woman. The book was subtitled, “The young men who make the money go.”

In 1975, when the Securities and Exchange Commission moved Wall Street from fixed commissions to negotiated ones, Siebert retooled Muriel Siebert & Co. into a discount brokerage, cutting her rate in half for individual investors.

Paper Billionaire

She went on to serve five years as New York State’s first female superintendent of banks. Following an unsuccessful bid for the Republican nomination for U.S. Senate in 1982, she returned to her brokerage, which she took public in 1996 under the holding company Siebert Financial.

The brokerage offered clients the option to trade online, and for two brief periods in 1999, as Internet-related stocks soared, her 90-percent-plus ownership stake made her, on paper, a billionaire. Within months, some $700 million of that disappeared.

Siebert, who had seen similar bubbles burst before, said she hadn’t let her hopes ride
with the share prices.

“The day-traders giveth and the day-traders taketh away,” she said in a November 1999 interview. Of her paper billion, she added: “At least I didn’t write a check for that amount.”

Siebert was born on Sept. 12, 1932, in Cleveland, the daughter of Irwin Siebert, a dentist, and the former Margaret Roseman.

Senate Bid

Describing herself as “very conservative fiscally and probably quite liberal in terms of people and human rights,” she stepped down in May 1982 to seek the Republican nomination to challenge Democratic Senator Daniel Patrick Moynihan. She lost to Florence Sullivan, a member of the state Assembly who went on to lose to Moynihan.

Siebert never married. Starting in 1999, she developed and promoted an academic curriculum to teach personal-finance skills to high-school students.

“Do not be afraid to go into uncharted territories,” she told Wagner College graduates at their commencement. “You might find some pretty good things there.”