Just last week, Atlanta-based Omni National Bank was closed by the Office of the Comptroller of the Currency. SunTrust acquired Omni's $400 million in insured deposits from the FDIC and six branches located across the country. It's also possible that regulators will force more mergers of equals among the large regional banks if the outcomes of the stress tests are negative, says Paul Miller, an analyst at Friedman, Billings, Ramsey, who covers large and mid-cap banking companies. Miller says that most of the companies that he covers are "very weak" on capital. He wrote in a recent note that investors should avoid purchasing shares of PNC until the Pittsburgh-based company can rebuild its capital levels. "PNC's credit quality is better than that of its peers. It will be a survivor, but its future capital structure is nearly impossible to predict," Miller wrote. "Given the significant risk of dilution, we would avoid the shares until the company is better capitalized and its ability to build capital through earnings is stronger." Regional banks aside for a moment, there are other financial firms that could throw their hats in the mix to make an acquisition. After the Lehman Brothers failure and BofA-Merrill Lynch merger agreement last fall, the remaining two securities firms, Morgan Stanley ( MS) and Goldman Sachs ( GS), became bank holding companies. Morgan Stanley has openly said it is looking for ways to build its deposit base, inferring that it is interested in buying a bank.