Citi University: Inside the Bank's CEO Alumni Network

A JPMorgan Chase spokesman declined to comment. In an interview this fall, Scharf praised Citigroup for what his time there taught him.

"Citi has an extraordinary global franchise. In my years there I participated and was able to learn and see how successful global institutions have built themselves to a point of success over time, and what functions well and doesn't function well," Scharf said in an interview in late October, when he was named Visa CEO. "I think my experiences at Citi will certainly help me navigate this company and its global growth."

Scharf is now competing head-to-head with former colleague and friend Ajay Banga, who took over MasterCard in 2010. Banga spent 13 years at Citigroup, running its international global consumer group and its Asia Pacific business before leaving for MasterCard in 2009.

A MasterCard spokesman declined to comment.

Robert M. Iommazzo, a managing partner at recruiting firm Seba International, says that Citigroup has historically groomed executives like Banga by rotating them through several different businesses and locations.

"The bottom line is, it's great training. You've got a lot of different constituents, a lot of different businesses, a sprawling empire," says Iommazzo, who recruits risk-management executives for Citigroup and other financial companies.

He also notes that most successful future leaders leave Citigroup with relatively grounded personalities; while CEOs like Banga and Jenkins might have healthy egos, "they're pretty down-to-earth guys … not your typical investment banker types."

Citigroup spokesman Mark Costiglio declined to discuss details of the bank's internal efforts to cultivate talent: "Citi has a longstanding commitment to the training and development of talented leaders who thrive in a culture that demands excellence and innovation," he said in an email.

But recruiters and former executives all singled out Citigroup's large foreign operations as an important proving ground for future industry leaders. Citi is the most international of the U.S. banks, and by running businesses abroad, its executives get a greater autonomy and responsibility than some other banks can offer their developing talent.

"It's a big, diversified financial services institution, and the heads of its various businesses have the opportunity to get the expertise, experience and exposure that makes boards comfortable hiring them as CEOs of other businesses," says Steven Eckhaus, a Wall Street compensation advisor and a partner at Katten Muchin Rosenman LLP. "What you're really observing more than anything else is a platform where they have an opportunity to learn."

Several industry members also point out one more practical reason for companies to poach Citigroup executives: shorter "gardening leaves" for defectors. Citi typically only requires a 75-day advance notice from senior executives who leave to work for rivals, compared with the standard of 180 days at most other big financial companies, according to recruiters. That means that Citigroup executives hired away by a competitor could start work again in less than three months, instead of keeping their new employer waiting for half a year. (Citi spokesman Costiglio declined to comment.)

To be sure, other banks and financial companies tend to have their own recruiting and training impact on the industry; American Express (AXP) alums, for example, are now running consumer businesses at both Citigroup and JPMorgan Chase. But among the other large banks, "you don't hear as much about their senior executives going off and heading up other companies as you do at Citi," says Rossi, now a teaching fellow at the University of Maryland's Robert H. Smith School of Business.