Online broking service CommSec says about 1,000 customers have been affected by a problem with its system this week.
One CommSec client told the ABC he was left out of pocket after trading on the system, because of a computer glitch.
After being contacted by the ABC, CommSec agreed to reimburse the client.
CommSec's Matt Comyn says the problem was a small, one-off incident.
"If any of our clients feel that they've suffered as a result of that they're more than welcome to talk to us and we will attempt to rectify any issues," he said.
