Shares of BankUnited ( BKUNA) swung wildly early Tuesday, as investors waited to learn the results of an auction to take over the struggling bank.

The Coral Gables, Fla.-based bank's stock fluctuated from a dip of 5% to a rise of 10% in a matter of 15 minutes. Recently, it was up 1.3% at 90 cents.

The Federal Deposit Insurance Corp. warned BankUnited that it may be forced into receivership if it is unable to raise up to $1 billion in fresh capital to cover escalating losses or find an acquirer, according to a regulatory filing earlier this month. The bank has not filed earnings statements for the past two quarters, but said it expects a second-quarter loss of $443 million, up from $66 million a year earlier.

The deadline for a solution was extended from Friday to Tuesday. Several players in the private-equity and banking space are reported to be involved in the FDIC's auction.

W.L. Ross & Co., the private-equity firm of billionaire distressed investor Wilbur Ross, has been vocal about its bidding. W.L. Ross teamed up with competitors Carlyle Group, Blackstone Group and Centerbridge Partners, and is being advised by former North Fork CEO John Kanas , to negotiate a deal.

Toronto-Dominion Bank ( TD) and Goldman Sachs ( GS) have also teamed up to throw their hats in the ring, according to several news reports citing anonymous sources.

J.C. Flowers & Co., the firm run by billionaire private-equity veteran J. Christopher Flowers, was also rumored to be interested in participating in a BankUnited deal. Under current law, each individual private-equity firm must own less than 25% of a bank, or 33% in certain cases, causing several groups to partner up on deals. Flowers did this with the acquisition of the failed California bank IndyMac Bancorp last year.

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