(Chris Goodney/Bloomberg) Stralem Traders often have to reassure their clients: 'Yes we have this under control. No, we won't lose your investment, and please, don't reconsider your options — no investment bank can do what we do.'

But 99-year-old Wall Street veteran Irene Bergman hasn't lost an account in the 20 years since Philippe Labaune, head of trading at Stralem and Company, has been there, Labaune said in an interview with Bloomberg.

The only time Bergman lost a portfolio was when she outlived her client.

Bergman, who is senior vice president at investment advisory firm Stralem and Co., has lived through numerous market bubbles, bursts and rises.

She escaped Nazi Germany before earning her family's money back, was at the front lines of Wall Street sexism in the 1960s, witnessed Apple Inc's legendary ascent (and missed it), and finally experienced her industry's transformation into a fast-paced, computer-driven and “much more competitive, much more knives-in-the-back” place.

In an world run by middle-aged men and quick-handed millennials who value speed, Bergman is an outlier who uses age and experience as her edge.

“The longer you’re in the business, the more pessimistic you get,” she said. "I’m able to get bullish, because when I look at a stock, I can imagine where it was 40 years ago.”

When asked by Bloomerg what her secret to succeeding in this cut throat world was, soft-spoken Bergman imparted her wisdom in an Manhattan apartment filled with paintings by old Dutch masters and French Louis XV chairs against the wall:

Don't be stupid.

Follow Bergman's advice, be smart and head to Bloomberg for the full story >>

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