EXCLUSIVE—Roboadvisor investment firm Betterment experienced service interruptions yesterday when customers flocked to its site and app after the Dow fell more than 1,500 points.

The firm has attributed these interruptions to “particularly high volume,” according to a statement the company sent Bank Innovation.

Betterment said in the emailed statement:

Due to particularly high volume, clients experienced log-in issues for approximately thirty minutes this afternoon. Accounts were secure throughout and portfolio management activities like rebalancing and tax loss harvesting continued. These issues have been resolved.

Betterment’s site appears to be running normally at the time of this reporting, but yesterday’s thirty-minute crash led to many frustrated customers, Twitter indicated, as Bank Innovation previously reported yesterday.

While company also notes that customer accounts were ‘secure’ during this period, that might be poor comfort for consumers who were locked out of their accounts as they watched the stock market strip money from their portfolios.

Betterment was not the only roboadvisory service to experience issues yesterday—Wealthfront customers also took to Twitter to vent their feelings.

Additionally, the company’s status as a roboadvisory firm, which relies more on automation than human guidance, means that its clients do not expect always and immediate service, according to persons with knowledge of the matter.

While the “high volume” led to log-in issues for Wealthfront and Betterment, rival online investment service Stash—a service which allows users to begin “micro-investing” in stocks with a minimum of $5—wanted to make sure its customers knew it was still up and running, tweeting:

Business as usual today. All Stash services are online and running normally.

— Stash (@Stash) February 5, 2018

To learn more about roboadvisors, join us on March 5-6, 2018 at the Parc 55 in San Francisco for Bank Innovation 2018. Click here to request an invitation.