The follow-up to two of a series of global stock market halts related to technology or cybersecurity this year come after the resignation of the head of the Tokyo Stock Exchange (TSE) earlier this week over a system failure.

The disruption in Tokyo halted trade in October for an unprecedented full day on the world's third-largest equities platform.

NZX Ltd was overwhelmed by trading volumes in March and April's coronavirus-driven sell-off, as well as a week of cyber attacks in August.

In Australia, the central bank and corporate regulator had expressed concerns over bourse operator ASX Ltd's trading systems after the glitch halted trade on Nov. 16.

"We take our role as a provider of mission-critical technology seriously and apologise to ASX, its customers and all those impacted", Nasdaq CEO Adena Friedman said on Friday.

She said the company was committing its "full attention and resources" to the issue.

NZX said an independent cybersecurity firm tasked with reviewing the cyber attacks had recommended several steps to strengthen security and closer communications with the broader cybersecurity community.

Fujitsu, developer of the Tokyo bourse's "Arrowhead" trading system which caused the outage, has halved its president's pay for the four months over the outage.

Traders and smaller investors flooded social media with complaints after the Australian outage, but most institutional players in the market have remained tight-lipped publicly.

"It does seem to me that they are becoming more frequent. They are also becoming more acute - the duration of the outages seem to be longer", said Brad Smoling, managing director at Australia-based Smoling Stockbroking.

(Reporting by Shruti Sonal in Bengaluru; Editing by Shounak Dasgupta)

By Shruti Sonal