Market announcements aren't appearing on the NZX this morning - but a cyber attack is not to blame.

Rather, the market operator says it's having problems returning to its regular system after giving its backup a workout over the weekend.

"As part of NZX's yearly testing programme, over the weekend we switched to our secondary data centre, and are experiencing a temporary issue with displaying our announcements on NZX.com," head of investor relations Simon Beattie told the Herald.

"Announcements are still being distributed in real time on our alternative site – announcements.nzx.com."

The alternative market announcement site was set up in late 2020 after a series of DDoS attacks swamped NZX's main site with connection requests, rendering it inaccessible.