"The exchange has been in regular contact with market participants throughout the period. NZX's current focus is on recommencing trading as soon as possible," Law said earlier this afternoon.
He confirmed there was no issue with the Nasdaq trading system, having earlier said NZX was working with Nasdaq to resolve the issue.
After the close of trading, NZX said normal trading will resume tomorrow with the problem resolved. A full investigation will take place over the next few days and an incident report released to the market.
"Any crossings and pre-negotiated deals effected today that could not be reported should be reported in the pre-open tomorrow morning, and flagged as late trades," it said.
Dual-listed Synlait Milk was the best performer on the index today, up 2.5 per cent to $12.50. A2 Milk, also listed on the ASX, rose 1.7 per cent to $12.39.
Scales Corp gained 1.9 per cent to $4.94. It expects a good export apple season will deliver full-year operating earnings at the top of the company's forecast range. The apple grower, food processor and exporter today reported a 22 per cent increase in net profit to $34.8m for the six months ended June 30 on the back of good growing conditions and better volumes through its logistics and pet food operations.
Arvida Group rose 1.5 per cent to $1.35, and Air New Zealand advanced 0.6 per cent to $3.29.
Tourism Holdings was the worst performer, down 3.6 per cent to $5.93. It announced plans to step up investment in its TH2 joint venture with RV maker Thor Industries, which will stop it from repeating another year of record profits.
The Auckland-based company reported a record net profit of $62.4m in the year ended June 30, of which $23.1m was an accounting gain from setting up the venture with Thor. Earnings before interest and tax before one-off gains rose 33 per cent to $63.5m on a 25 percent increase in revenue to $425.9m. It will invest around $15m in TH2 this year, which will mean net profit will fall from 2018's record.
Skellerup Holdings fell 0.9 perc ent to $2.15 and Sky Network Television dropped 0.8 per cent to $2.43.