Shares of Doral Financial plunged 20% in premarket trade Tuesday after the mortgage banking company said in a filing that it failed to settle a tax dispute with Puerto Rico's Treasury Department. Doral and the Treasury Department will now go to court on Sept. 16 to Sept. 18. Doral had filed a lawsuit against Puerto Rico's Treasury Department, seeking to collect the $229 million owed to Doral under a 2012 closing agreement between the two parties. Doral and the Treasury Department had recently entered into a court-supervised negotiations to settle the claims, but those talks ceased on Aug. 25 after the two parties failed to reach an agreement. Doral's stock had more than tripled over the last three months through Monday, but were still down 47% year to date, compared with an 8.1% gain in the S&P 500.

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