The Investment Industry Regulatory Organization (IIROC) says it "deeply regrets" the accidental loss of the device and is in the midst of contacting clients who may now have their personal information put at risk.
Canada's financial industry regulator said Friday the missing data is from clients at 32 firms, but would not disclose which ones.
The data had been obtained by the IIROC through "regular compliance reviews."
“IIROC deeply regrets this unfortunate but isolated incident and apologizes for the disruption caused to clients and the affected firms," president and CEO Susan Wolburgh Jenah said in a statement.
"The protection of confidential information is critical to us and we have taken steps to address the situation and to immediately strengthen our internal controls."
An internal investigation has been launched and the group has brought in a third-party security expert to help it identify what type of information may have been lost.
It's unclear where the device was misplaced and what type of information it may have contained.
"We are concerned that disclosing further details surrounding the incident may put clients’ information at greater risk of being targeted for unauthorized use," spokeswoman Lucy Becker said in an email.
IIROC said there was no evidence that there had been any unauthorized attempts to access the portable device.
The group will be setting up a dedicated call centre beginning Monday for any inquiries from concerned investors and will place a six-year alert flag through Equifax Canada on any clients' credit files that are at risk of being breached.