PASADENA, Calif. ( TheStreet) -- The private equity team that's building the OneWest banking enterprise across the recession-ridden state of California has made great progress over the past nine months, though it will probably take years to reap the full rewards of that work through a sale or public offering.

The former IndyMac Bank was sold to a group of private equity gurus, led by Dune Capital Management's Steven Mnuchin early last year. The transaction was completed on March 19, months after the Federal Deposit Insurance Corp. seized the failed thrift.

The investors -- including J. Christopher Flowers, John Paulson, Michael Dell and George Soros -- are employing a roll-up strategy for their investment. It goes like this: Buy one bank to start a holding company, this one called IMB HoldCo. Then buy other failed or troubled banks throughout the region to form a medium- to large-scale banking enterprise. Use hard bargaining or generous loss-sharing agreements with the FDIC to acquire them on the cheap. Expand business lines through such acquisitions. Once integrations are complete, sell the whole, healthy entity to another bank, or in the public market, generating heady profits.

The process, of course, is easier said than done, but IMB has made great strides in a short amount of time. The consortium recently set its sights on a struggling lender called First Federal based in Santa Monica, Calif., roughly 25 miles away from OneWest's Pasadena headquarters. When First Fed failed on Dec. 18, OneWest acquired its $6.1 billion in assets for about $1.5 billion, and entered a loss-sharing agreement with the FDIC on nearly the entire loan portfolio.

While IndyMac was known for its big mortgage business and extensive online banking operations, its branch network was relatively meager. Mnuchin recently told the Wall Street Journal that First Fed, known more as a traditional S&L, was the group's "No. 1 strategic target." The 39 First Fed branches account for more than half of the 72-branch OneWest network.

"You've got arguably five or six of the greatest private equity investors ever behind this purchase -- right there you should take notice," says Andre Peschong, an investment banker and partner with Bridgewater Capital, who runs the blog Deal Flow Diaries. "These are not traditional private equity investors, these are opportunists."

The typical buyout strategy involves a cheap deal, high leverage, a quick restructuring and an exit bearing a 10% to 11% return on capital within a couple of years. There were more than a few private players hoping to earn a pretty penny on a raft of bank failures, using taxpayer incentives as a crutch. As the first successful private equity acquisition of a bank that succumbed to the financial crisis, competitors have closely monitored OneWest's progress.

"A lot of private equity groups I spoke to were chomping at the bit to get in there and buy banks about a year ago," says Kevin Mulvaney, a professor at Babson College who teaches a series of M&A and has a background in commercial banking. "They were hungry animals in the forest, so to speak."

However, the FDIC issued a policy statement in August meant to crimp any "get rich quick" schemes involving the public's loans and deposits. It requires a 10% capital ratio -- tying up money for loan-loss reserves that could otherwise be put to more profitable use -- and prohibits investors from selling or transferring assets for at least three years.

Of course, the potential to get rich didn't vanish, it was just made the process more difficult and less quick. That still leaves a sizable roster of interested buyers with more patience than the fast-money junkies.

Bridgewater Capital's Peschong notes that Carlyle Group, The Blackstone Group ( BX - Get Report) and Fortress Investment Group ( FIG), are also known for structuring deals with far-off profit horizons. Carlyle, Blackstone, Centerbridge Capital Partners and Wilbur Ross's WL Ross & Co. were among the partners that acquired the failed Florida thrift BankUnited in May, before the FDIC rules came out.

Interest seems to have waned in the intervening time, especially since Ross assured the FDIC in a public letter that his firm would "never again bid" on a bank if stricter rules were adopted. Yet private buyers may be taking a "wait and see" approach and playing a bit of hardball with the FDIC. The regulator flexed its muscles to show it was acting in the public's best interest, and make clear its preference for bank buyers. But the fact remains that there's a shortage of healthy banks to acquire their fallen brethren.

Large ones like Bank of America ( BAC - Get Report), JPMorgan Chase ( JPM - Get Report), Citigroup ( C - Get Report) and Wells Fargo ( WFC - Get Report) have their own problems to contend with, and are being threatened by proposals to whittle down their size, not build it up further. Uncertainty about future capital requirements, and how far the commercial loan market will fall, has prevented others from stepping up to the plate.

That leaves the private set.

"In the last significant downturn, when I was a regulator, there were a number of large, healthy banks available to pick up these institutions," says Walt Mix, one-time commissioner of the California Department of Financial Institutions, referring to the savings-and-loan crisis of the 80s and 90s. "Now the regulators have fewer options."

Mix, now a financial M&A consultant at LECG, says business has picked up quite a bit recently. He expects to see a wave of bank deals in the coming months, especially because California's bleak fiscal state leaves room for plenty of distressed M&A.

"Early this year, we're expecting to see more private equity players coming into the space," says Mix, who recently assisted on East West Bancorp's ( EWBC - Get Report) deal to acquire the assets of the failed bank United Commercial. "We're expecting to see regulatory approvals, and that will add buyers to the system and put forth the prospect of additional capital for banks in troubled parts of the country."

It's also worth noting that the FDIC left itself a good deal of leeway in structuring deals with private buyers. Kenneth Kohler, a partner at Morrison & Foerster who represents financial firms on the West Coast, but does not regularly represent OneWest, notes that a policy statement is just a set of publicly-announced guidelines, not a hard set of rules. The FDIC can waive or alter provisions, depending on the economic situation and its trust in the institution's management.

"It's a little bit difficult to talk about OneWest, because there probably is a real-world answer about what their understanding regarding an exit is with the FDIC, but we don't know what it is," he says.

For instance, while the IndyMac deal occurred pre-policy statement, the First Fed deal did not. One can assume that the IMB partners are okay with the capital requirements and three-year horizon, though one can also assume the time frame doesn't reset with each new deal. These remain assumptions, however, because the FDIC won't comment on deal specifics beyond its press releases, and OneWest did not make an executive available.

What is publicly known about OneWest is that it's already one of the largest banks in Southern California. It's also quite profitable, having earned $891 million during the first nine months of 2009.

It may take a few more years to reach Mnuchin's stated goal of 100 to 150 branches, get to the other side of the recession, and to a point at which bank assets are better valued. That could be especially true for OneWest, which operates in one of the worst-hit areas of the country in terms of housing, unemployment and economic growth.

Still, from the looks of it, that's okay with OneWest. Chris Flowers and his partners may have yet to achieve the "tremendous fortune" he predicted in the early days of the fallout -- but they seem to be lining themselves up to do just fine, whether by offering the entire bank in an IPO, selling shares outside of their controlling interest to build it out further, or offering it to a competitor.

"I don't know if OneWest has decided its exit strategy with any specificity," says Kohler. "But they're about building a business, not flipping."

-- Written by Lauren Tara LaCapra in New York.