For many bankers, Thursday night's celebration of American Banker's Most Powerful Women in Banking began with a walk down the red carpet, or a stroll around a chandelier-lit foyer, while sipping a glass of sparkling wine.

But the festivities at the Waldorf-Astoria Hotel in New York quickly struck a reflective tone, as some of the industry's top female leaders lamented the fact that the ranks of women occupying C-suites have thinned over the last couple of years. The impending retirement of Irene Dorner as chief executive of HSBC USA would leave just two women — KeyCorp's Beth Mooney and Ally Bank's Barbara Yastine — at the helm of major U.S. banks.

"At the CEO and C-suite levels, the ranks are smaller this year, smaller still than the year before," Mooney said in her keynote address.

"A few successful women have made it, and then they disappear, and it leaves a gap," added Dorner in what amounted to be her farewell address before she steps down next month.

It wasn't supposed to be this way. The year began on an inspirational note, with the swearing-in of Janet Yellen as the first woman chair of the Federal Reserve Board. Still, Mooney, who, for the second consecutive year was honored as the industry's most powerful woman, urged her female colleagues to maintain a sense of "constructive impatience," and to define their own dreams of obtaining an executive role.

"While I think it is important to acknowledge the lack of depth of women in the C-suite, I think it's more important to transcend it," said Mooney. "I don't believe we should be mired in an unproductive rhetoric about how it should be or play the victim."

Women who ascend the corporate ladder, she said, have a responsibility to help women behind them "develop the right skills and mindset." "I think of it as carrying while we climb," she said.

In a moment that captivated the audience, Mooney told the story of how she decided that she wanted to run a bank.

Years ago, while working at Bank One (which is now part of JPMorgan Chase), she was talking with a group of senior women executives on the way back from a dinner hosted by John McCoy, the bank's CEO at the time.

Mooney said her colleagues couldn't stop talking about McCoy's wife, Jane, praising her charm, grace and social position. "They all wanted to be her," she said. "And she was indeed lovely in every way."

Mooney said she grew quiet — "a rare occasion," for her, she said as an aside — while she listened to her friends talk up the virtues of being a perfect host. "I can tell you what was going through my head was a lightbulb moment — a moment that changed my career and my life," she said. "I realized that I didn't want to be Jane McCoy. I wanted to be John McCoy."

Now that she's made her way to the top of the executive ranks, she said, it's her duty to "make the way forward" for women who have the same dream. Many of Key's senior executives are women and, in fact, two of Mooney's direct-reports, Maria Coyne and Amy Brady, were also honored at Thursday's gala. Coyne, who runs Key's branch network, was ranked the No. 18 Most Powerful Woman while Brady, its chief information officer, was the No. 6 Woman to Watch.

Dorner echoed the call to create a pathway for women to the executive suite while accepting a lifetime achievement award for her career in banking.

"We need a pipeline of talented women in the system, and this is about critical mass," she said. "If we stick to the current rate of turnover, it's going to take 75 years to reach parity."

Dorner, who was promoted to CEO at HSBC USA in 2010, has steered the bank through some of its most difficult periods, including being hit with $1.9 billion in penalties for violating anti-money laundering laws.

In her speech, she discussed the merits of stepping into the spotlight at a time of difficulty.

"I can honestly say that the greater the crisis, the greater the craziness, the greater my sense of ownership and responsibility and emotional attachment," she said.

The ability to "look and sound like a CEO despite everything" is a leadership quality she's learned since taking over at HSBC.

Additionally, she said that good leadership means focusing on "long-term, sustainable outcomes," particularly at a time when new regulations and large legal settlements are shaping the future of the business.

"If the outcome is supposed to be to create a business environment that's open, transparent, and attracts inward investment, then let's try to make a legal environment that is clear and defined," she said.

Recent settlements over financial crisis-era lawsuits, she suggested, have failed to meet that standard.

"Settlements behind closed doors may well feel safer for the individuals involved, but they don't drive the right outcome," she said.

She closed her speech with a poem that a coworker gave to her while HSBC was going through a hard time. Explaining its significance, she said: "It's surprising what you can find within yourself when you're up against it."

Dorner, who will retire in just a few weeks, said that serving as CEO was "the very best role" of her entire career.

"Man, it really has been a great ride," she said, with her characteristic enthusiasm, as she walked off the stage.

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