GunnAllen was has been shuttered by Finra for net capital violations, but client money will be safeguarded, said a source close to the situation.
The industry regulator had warned Tampa-based GunnAllen last week that it needed a capital infusion over the weekend in order to stay in business.
When that did not happen, the regulator closed the broker-dealer, it said on Monday.
The source said that clients' money is not at risk because GunnAllen's clearing firm, Ridge Clearing and Outsourcing Solutions, will take over the accounts. But the broker's 400 employees are out of a job.
GunnAllen could not be reached for comment.