Aug. 27 (Bloomberg) -- BankUnited Financial Corp., the Florida lender ordered by regulators to raise money or lose its ``well-capitalized'' status, fell 19 percent after Stifel Nicolaus & Co. said it may be unable to survive.

Capital is ``necessary to protect the solvency of the company,'' analyst David Bishop said today, cutting his rating on the shares to ``sell'' from ``hold.'' The Office of Thrift Supervision may drop the lender to ``adequately capitalized'' if it fails to raise at least $400 million, the Coral Gables, Florida-based BankUnited said in a regulatory filing.

BankUnited tumbled 27 cents to $1.16 in Nasdaq Stock Market trading today, the most in more than a month. The shares are down 83 percent this year. Spokeswoman Melissa Gracey said BankUnited would not comment on analyst reports.

``We see the prospects for viability increasingly fraying,'' Bishop said in a note to investors. ``While any raise will be dilutive to tangible capital, at this point, we view this as a secondary concern behind the ability of the company to continue as a going concern.''

BankUnited is the largest lender based in Florida, a state with the third-highest foreclosure rate in the U.S., according to RealtyTrac Inc., an Irvine, California-based seller of foreclosure data. The lender said in June it was seeking $400 million to add to capital after losses on $10 billion in home loans. About 60 percent of the lender's loans are secured by Florida property, the company said in a filing.

BankUnited has total assets of $14.2 billion and operates 85 branches in 13 Florida counties including Miami-Dade, Palm Beach and Sarasota, the company said in a August statement. The lender has $7.61 billion in total deposits, BankUnited said in a filing.

To contact the reporter on this story: Linda Shen in New York at lshen21@bloomberg.net

Last Updated: August 27, 2008 16:34 EDT