Stacey Cunningham always knew she was one of few women to ever work on the trading floor — but she didn't let that deter her from pursuing a career in a male-dominated industry.
This year, she became the first female president of the New York Stock Exchange — the largest stock exchange in the world, which, notably, didn't have a first female member until 1967 — about 175 years after it was founded.
"It's helpful to tell my story because it means that other women can hear that there are opportunities out there available to them that they may not have realized," Cunningham says in “Firsts,” TIME’s multimedia project featuring candid interviews with dozens of groundbreaking women.
Cunningham started as an intern at the stock exchange in 1994, eventually becoming a trading floor clerk.
"You definitely stand out as a woman on the trading floor, but I never felt singled out," Cunningham tells "Firsts." "I went down there and I wasn't intimidated. I played my own game, I was who I was, I didn't try to be one of them."
"I made it clear. I drew my own boundaries. I knew what was OK for me," she says. "If there was any time somebody said something that I felt was inappropriate or just made me uncomfortable. I made it very clear right away, and then it never happened again."
Throughout her career, Cunningham has had numerous jobs in and out of Wall Street. She left finance to study at culinary school, then returned to the Financial District with several roles at NASDAQ. When she rejoined the New York Stock Exchange, she eventually became its Chief Operating Officer — and, three years later, its 67th president.
When speaking to "Firsts," Cunningham offered some sage advice for women launching their careers: "When you do feel outnumbered, that's OK. You don't have to fit in quite the way people might expect you to."
Watch the rest of the "Firsts" videos at Time.com/Firsts.