They called her “the Witch of Wall Street” and Hetty Green didn’t seem to mind.

Her singular focus on wringing every ounce of value out of her money made her wealthy and, more importantly, allowed her to maintain control over her own life.

“It is the duty of every woman, I believe, to learn to take care of her own business affairs,” she said.

While her ideas might have been radical at the time, her investing strategy was not. Hetty believed in research, patience, discernment and value. She claimed she never made a business deal without sleeping on it overnight.

“I believe in getting in at the bottom and out on top,” she said. “I like to buy railroad stocks or mortgage bonds. When I see a good thing going cheap because nobody wants it, I buy a lot of it and tuck it away.”

Her estimated worth at the time of her death at the age of 82 in 1916 was between $100 million to $200 million (equivalent to $2.35 billion to $4.7 billion today), the vast majority of which was earned via her own efforts. In fact, Hetty had to bail out her husband Edward more than once and left him after she had to put up $500,000 of her own money to cover his losses when his bank failed in 1884. She also bailed out the city of New York with a $1.1 million check in 1907 and negotiated her repayment in short-term bonds.

A firm believer in pre-nuptials, Hetty not only made Edward sign one prior to their marriage, she also insisted her daughter’s husband sign one and encouraged all women to protect their assets in marriage.

So frugal she wore the same single black dress and, reportedly, undergarments until they fell apart, Hetty remains listed in the Guinness Book of World Records as the greatest miser. However, she also quietly supported many charities and said she believed her most valuable assets were the jobs that her wealth created through her investments in this country.