They've organized stress tests, overseen initial public offerings and made it to the executive suite—all before turning 40.

Meet some of the banking industry's youngest chief financial officers. Aside from ambition, what makes these young CFOs notable is that they cut their teeth in banking at the peak of the subprime mortgage bust. It was a once-in-a-generation opportunity to learn about the risk in banking by putting them in the front row. The opportunity put these young bankers on the fast-track to the one of the top spots in their organizations.

"I would have hated to come through during the great, wonderful years of 2003 and 2007, when things were just peachy keen, and you could charge whatever you wanted and leave at 12 noon to go play golf," said David Beaver, 32, who serves as CFO at Uwharrie Bank in Albemarle, N.C.

Not surprisingly, the young CFOs have sterling sets of credentials. Their resumes list advanced degrees and experience at large accounting firms. They also acknowledge a considerable amount of good luck.

"Timing is everything and is sometimes out of your control," said Mark Chancy, who was 40 when he was named CFO of the $186 billion-asset SunTrust Banks in 2004. He was also named CFO of Robinson Humphrey, the investment bank acquired by SunTrust in 2001, when he was 33.

Analyst training programs offer the best way to gain a wide range of experience in a short amount of time, said Chancy, who is currently SunTrust's wholesale banking executive. "Learning the different businesses, learning how to construct a different capital structure, the analytical work, the financial statement review — it's a terrific first job," he said.

While Chancy benefited from a structured training program, others were essentially baptized by fire.

These young CFOs were trained in a topsy-turvy economy following the 2008 downturn, when no one knew what was going on or what would happen next. They spent their formative years analyzing balance sheets saddled with problem assets. They watched their mentors struggle to keep their banks afloat through the crisis. And they took good notes.

Nicole Carrillo, the CFO of the $5 billion-asset Opus Bank in Irvine, Calif., had an up-close view of the financial crisis while working as a bank auditor in California.

Carrillo, 34, joined Opus four years ago, after a decade-long stint at KPMG. When the markets began to turn in 2008, she witnessed up-close some of the country's biggest bank failures.

"There was a period of two years when I was changing clients all the time because they were just going under," Carrillo said. Her clients included Countrywide Financial, which was acquired by Bank of America, and Downey Savings Bank, which was acquired by U.S. Bancorp from the Federal Deposit Insurance Corp. following its failure.

It was a crash course in financial management. The banks that survived understood that "things don't happen in isolation" in financial markets, she said. They had also invested in state-of-the-art forecasting software, and could predict the fallout from faulty mortgages.

"Honestly, my clients that did not make it were the ones that we struggled with every quarter, where we repeatedly had to ask, 'Why didn't you downgrade those loans?' " Carrillo said.

Carrillo's experience during the crisis has informed her current role as CFO at Opus, a fast-growing community bank that, she said, is expected to top $10 billion in assets within five years.

After watching small banks struggle with analytics, she's made it a priority at Opus to rely on technology for as many processes as possible—even with groups outside of her supervision. For instance, she recently worked with the credit division to automate the bank's allowance calculation.

"We should be able to automate as much as we can, to dig in and understand trends," Carrillo said. "To really get smart on credit, I have to understand what's driving it."

Holly Flowers, CFO at the $137 billion-asset Fifth Third's Cincinnati affiliate, found her leg up in the industry with the stress testing exercises that became a cornerstone of risk management following the crisis.

Flowers, 31, joined Fifth Third in 2007, as the subprime crisis was beginning to swell, after finishing her master's degree in accounting. She had originally planned to pursue a career in public accounting, and had completed an internship at Ernst & Young.

But she signed up for Fifth Third's leadership training program because she liked the idea of doing rotations through several departments.

On the advice of her mentor—James Leonard, who currently serves as Fifth Third's treasurer—she signed up during her second year at the company to join the business planning and analysis division. That gave her an opportunity to help manage the bank's first stress test with the Federal Reserve.

"I didn't realize how many people would have to come together to build out something like that," she said.

Flowers recently moved from the corporate side of Fifth Third to take a job as CFO of its largest affiliate. She hopes to continue moving throughout the bank. "I would love to see myself as a CEO someday," she said.

Banking's youngest CFOs have also earned the respect of industry analysts. Age doesn't matter as long as CFOs have the right experience and credentials, they say.

"All boards are on close watch to really put the best, most capable talent into those kinds of jobs that they can. And failure to do so—failure to pick the right person in this day in age in banking, in this regulatory environment—will come out, and will be noticeable," said Tim O'Brien, an analyst with Sandler O'Neill.

In other words, it is worth keeping tabs on this class of up-and-comers. They've quickly ascended the corporate ranks at a time when fewer young people are entering the field. The number of MBAs entering finance has declined to 26% in 2014 from 30% in 2010, according to the Graduate Management Admissions Council, a nonprofit group representing graduate-level business schools.

Despite the prestige of the job title, being a young CFO comes with its fair share of challenges. Long hours can be difficult for executives with young families.

"For me, family is one of the most important things, but I have an innate desire to be successful," said Daniel Hobbs, a business line CFO at the $119 billion-asset Regions Financial. "So I'm constantly having to navigate that balance."

Hobbs, 41, took over as CFO three years ago for the consumer services, operations and technology division, where he oversees $11 billion in assets. He said it's "still to be determined" if he wants to land a top CFO spot at a large bank, citing the possibility of late nights and time away from his wife and two children.

"The further you go up, that's one of the things you have to think about," he said.

There's also the burden of having to earn the respect of older colleagues. Landing an executive-level job is usually a late-stage career move. Nearly 80% of the CFOs who responded to a survey by American Banker Research were older than 40, while the median age was 50. Additionally, 46% of the respondents say they've been a CFO for more than a decade.

"Early on, you feel like you have to prove yourself," said Beaver at the $517 million-asset Uwharrie.

He said he received some pushback—mostly from people outside the bank—after he received his promotion as CFO.

" 'You are awfully young to be in this position. Can you handle the stress?' " colleagues told him, he said. " 'Can you handle the responsibility and not be arrogant?' "

Beaver said he moved up quickly at Uwharrie because of the mentoring he received from several of the bank's top executives. One mentor, in particular—Bob Bratton, the bank's previous CFO—left a lasting impression on him.

During the height of the financial crisis, Bratton offered this advice: "Have the memory of an elephant. Don't forget this [time]. Things turn around, rates rise, but don't forget this."

The advice shaped Beaver's approach to financial management. While times are better now, "it will cycle back. It always does," he said.

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