Following the loss, the AICPA is offering affected members a year's worth of free credit-monitoring services. The incident has also prompted the group to begin deleting all Social Security numbers from its member database.

While a note posted on the organization's Web site says the collection of Social Security numbers has been a long-standing procedure, it added that "we will cease collecting and maintaining them, except in limited circumstances. And even for those, we are accelerating our efforts to develop other means of uniquely identifying our members."

News of the AICPA breach comes amid a flurry of similar disclosures in recent days. By far, the biggest was the May 22 disclosure by the U.S. Department of Veterans Affairs that it had lost personal data on more than 26.5 million veterans discharged since 1975. Since then, the agency has admitted that the breach may have exposed personal information on about 2.2 million active-duty National Guard and Reserve troops as well.

Since then, there have been similar disclosures elsewhere, including Texas Guaranteed Student Loan Corp., a Round Rock, Texas-based nonprofit organization. TG said that an outside contractor lost an unspecified piece of equipment containing the names and Social Security numbers of approximately 1.3 million borrowers.

On May 26, Sacred Heart University in Fairfield, Conn., announced that one of its computers had been hacked into, resulting in the potential compromise of data belonging to 135,000 alumni and would-be students. And earlier this month, a password-protected laptop containing credit card information on more than a quarter-million Hotels.com L.P. customers was stolen from the car of an auditor at Ernst & Young LLP.