Had I been asked that question not terribly long ago, I may have responded with a definitive, "When pigs fly."

Well fellow Fools, it's entirely possible that somewhere in the world, swine are aloft, because not only am I recommending Citigroup (NYSE:C), but just last week I purchased shares myself. Here are three quick reasons why.

1. Great stress-test performance
Citi's performance on the 2013 Comprehensive Capital Analysis and Review, the Federal Reserve's official moniker for its yearly stress tests, was both impressive and surprising. The superbank managed to pull off an actual Tier 1 common ratio of 12.7% and a stressed minimum of 8.3%. 

The normally indomitable Wells Fargo (NYSE:WFC) only managed an actual Tier 1 common ratio of 9.9% and a stressed minimum of 7%. JPMorgan Chase's (NYSE:JPM) numbers were 10.4% and 6.3%, respectively: this from another bank with a supreme reputation for risk management and steadiness.

And recall that it was only last year that Citi failed its stress test. From "flunk" to "pass-with-flying colors" in a year's time is more than any industry observer or investor could ask for, at least as far as this metric goes.

2. Impressive leadership performance
This relates directly to Citi's performance on the 2013 stress tests. Citi may have passed with flying colors, but investors received no dividend increase or share buybacks in return. Why? Did the Fed deny Citi's request, despite the bank's impressive performance?

No. Citi leadership didn't even ask the Fed to consider any proposed capital-return actions. As far as I know, no official reason has been given, but my hope is, it's because CEO Michael Corbat is serious about turning his bank's fortune's around.

Sure, shareholders and potential investors would have loved a dividend increase or some share buybacks, but I think Corbat has his eye on the long-term performance of his bank.

Bank of America (NYSE:BAC) performed worse on the 2013 CCAR than Citi -- with an actual Tier 1 common ratio of 11.4% and a stressed minimum of just 6.8% -- but CEO Brian Moynihan decided to buy back $5 billion in B of A shares. I'm happy with the course Corbat is taking, and I'm saying this as a shareholder.

3. More impressive leadership performance
Okay, maybe this third point of persuasion is a bit of a cheat. What can I say? Leadership is very important to me. It's the primary reason I'm invested in both Goldman Sachs and JPMorgan: In my opinion, they're run by the sharpest CEOs on the banking block.

I'm beginning to think Corbat's not far behind. Aside from his steely decision not to return any capital to shareholders, he recently told a group of bank executives (in an attempt to explain how bank executives would be judged moving forward) that, "You are what you measure." 

My first reaction was, how terribly boring. But my next reaction was, how terribly responsible, thoughtful, and bankerly. As fun as it is listening to and reading about the swashbuckling CEO of JPMorgan, Jamie Dimon, that type of banker is precisely what Citigroup doesn't need right now.

Citi needs someone low key, low drama, and steadily thoughtful. Someone who's going to come in and calmly and coolly begin applying standards. Citi's such a big organization, you really have to. Corbat may be that man.

Foolish bottom line
I'm not telling anyone to go out and buy big into Citi right now. It still has a long way to go and a lot of cleaning up to do. The bank's balance sheet is still recovering from many bad decisions made during the housing boom.

But the bank may finally be starting to make the turn toward steady solvency and profitability. And I believe it's worth it to at least take a small position in it. Sooner or later, Citigroup was going to start turning itself around, and I think that time is now.