That report was suspected to have been the result of the paper misinterpreting a fictional summer series by Le Monde. As The New York Times explained:
The series, “End of the Line for the Euro,” looked at how a collapse of the single currency might play out, against the backdrop of French presidential elections next year. While the 12-part story was clearly labeled as fiction, it named real banks, like Société Générale, whose shares plunged 15 percent last Wednesday, prompting the bank to deny speculation that it was in financial trouble.
In an article that appeared in the print edition and online version of the Mail on Sunday on 7 August 2011, it was suggested that according to Mail on Sunday sources Société Générale, one of Europe’s largest banks, was in a ‘perilous’ state and possibly on the ‘brink of disaster’.
We now accept that this was not true and we unreservedly apologise to Société Générale for any embarrassment caused.
It’s not clear why the Mail chose to issue a second apology now.
Correction: This post mistakenly referred to the Daily Mail, rather than The Mail on Sunday, in two references. The offending article and resulting apology were both published by The Mail on Sunday.