After months of criticising "criminally careless" government departments for losing confidential records, the company has been forced to send out an embarrassing letter telling journalists they may now be at risk of identity theft, MediaGuardian.co.uk can reveal.
Even those who no longer work for either Associated Newspapers, which also publishes the Mail on Sunday and the Evening Standard, and regional newspaper publisher Northcliffe Media have been affected and contacted.
The letters from the Associated Newspapers group finance director, Simon Dyson, and his Northcliffe counterpart, Martyn Hindley, tell recipients that their "name, address, bank account number and bank sort code were the sensitive data lost" when the laptop was stolen last week.
Dyson and Hindley reveal the laptop was "password protected" but tell recipients to contact their banks and also "consult the government website … for advice on avoiding or dealing with identity theft".
The letters add: "The likelihood is that this theft was carried out in an opportunistic manner by a thief who will not realise that there is any personal data on the computer and who may just erase what is on the hard drive in order to disguise the fact that the computer is stolen.
"We have, of course, notified the police of the theft of the laptop and are talking to the Office of the Information Commissioner about what has happened.
Associated and Northcliffe also apologise to those affected and say that since the incident, which was caused by a "technical issue", security procedures have been "strengthened".
Associated Newspapers has been at the forefront of coverage of the recent bank and government department missing data scandals, so the incident is likely to cause embarrassment.
In May, the Daily Mail attacked "blundering banks" for "misplacing [their] customers' private personal information".
Last December a leader article in the Mail called the recent data loss scandals involving the NHS and government departments "criminally careless".
A Daily Mail & General Trust spokeswoman said: "DMGT confirms that a laptop company computer containing certain confidential information was stolen last week.
"The password-protected computer contained limited information on some current employers and suppliers from the group's newspaper division.
"DMGT has informed the police about the incident. DMGT has contacted all those affected and apologised to all those affected by this breach in security."
(the subject line is the Daily Mail's headline for similar Govt laptop losses)