The Australian Web site of brokerage E*Trade was hit by a "malicious" cyber-attack over the holiday period, leaving some customers unable to access accounts.
According to the Sydney Morning Herald, a denial-of-service-style hit saw the site bombarded with thousands of e-mails just before Christmas.
The company shut off access to overseas customers as it carried out risk assessments on countries, with some users locked out of accounts for two weeks.
Some customers in Australia also had "intermittent access" for two days, a spokesman told the SMH, adding that the site's security was not breached during the incident.
Spam knocks E*Trade offline - Sydney Morning Herald