Thacher Proffitt & Wood didn’t have a lot of time left when Sonnenschein Nath & Rosenthal entered the picture two weeks ago.

The announcement late Sunday that Sonnenschein would hire 100 lawyers from the Wall Street firm signals the end of Thacher, which saw its fortunes fall as the securitization market collapsed. A partner at Thacher confirms the firm is expecting to announce dissolution plans by Dec. 31. Yet it could have been much worse had a deal not been struck by then or under other arrangements, lawyers involved in the transaction say.