The Serious Fraud Office is investigating international currency and derivatives trader WSD Group.
The Serious Fraud Office says WSD allegedly misled investors about how their money was used, while there are claims some of it has gone missing.
SFO chief executive Adam Feeley says the investors are mainly overseas, and it's important to protect the reputation of New Zealand's financial system.
Mr Feeley says the group of companies, recently controlled by former Wall Street Banking Corporation director Riaz Patel has previously been investigated by authorities in the Cook Islands and India.
He says the information the office acquired at the time of those investigations gave no indication or suggestion of wrong-doing in New Zealand.
Mr Feeley says the office has acted on additional information received since then.
The SFO has 23 investigations underway, involving losses of over $630 million, he says.
It has also taken prosecutions in another 32 cases, with losses of about $250 million.