The report said that an unencrypted portable hard drive was stolen from the car of an LPL representative on 24 February, according to a letter sent last month by LPL to the attorney general of New Hampshire.

The advisor, Christian D'Urso of StoneRidge Wealth Management in Beaverton, Oregon, had one client in New Hampshire, the letter is quoted to have said.

The firm declined to comment when contacted by this publication.

As a result of the theft, private client information, including names, addresses, dates of birth and Social Security numbers “may have been breached,” Marc Loewenthal, LPL's senior vice president and chief security and privacy officer, wrote in the letter, the publication said.

LPL has had to deal with a security lapse involving one of its reps before. In 2007, the firm reported that computer hackers had compromised the login passwords of 14 financial advisors and four assistants, the publication said.

The wealth management industry has been confronted with a number of security lapses recently. In Switzerland, HSBC Private Bank for example suffered the theft of thousands of client account details from its offices in Geneva. Meanwhile, confidential client information at the Icelandic-based private bank, Kaupthing, ended up on a public website, Wikileaks, last year.

LPL Financial describes itself on its website as "one of the nation's leading diversified financial services companies and the largest independent broker/dealer supporting almost 12,000 financial advisors nationwide".