Today has been the worst day on the New Zealand sharemarket since 2011.

The NZX50 has plummeted an astounding 2.6 percentage points.

Craigs Investments Partners' Mark Lister said it comes off the back of a very weak trading session in the US on Friday.

He said our market's been one of the strongest performers in the world - up 18 percent year-to-date and more than 30 percent in the past 12 months.

"As a result, it has been priced to perfection. So maybe that's why our market is down a little more strongly than some of the others around the region today."

Mr Lister said the markets are substantially off the boil, but it's just one day's move.

"The economic data is still very strong particularly here in New Zealand. I suspect a lot of investors have actually seen it as a bit of a buying opportunity if anything."