Milford confirmed it is working with the FMA in respect of a market investigation. It said the investigation concerns an individual trader employed by the firm and certain specific trades.

"The investigation does not have any implications for client funds and has no impact on the day-to-day operations of Milford. Milford looks forward to completion of the investigation."

It is believed that the trades in question were conducted about a year ago. They came to the FMA's attention from the NZX.

Morningstar said it had not included any information about the FMA investigation in any research or publications for investors or the financial services industry.

“The allegations are still subject to ongoing investigation by the regulator. We have contacted Milford Asset Management and have received formal written confirmation that the investigation does not have implications for client funds and has no impact on the firm’s day-to-day operations. We have therefore decided to leave our existing ratings unchanged.”

Fundsource, now Morningstar’s only major competitor, was also not making reference to the investigation.

Sam Stanley said: “We just leave it up to the parties involved, which is FMA and Milford.”

Although the investigation was sparked by the NZX, which owns Fundsource, Stanley said he had no extra insight into what was happening. “We have really clearly defined parts of the business. The side that would get involved in that is the compliance, regulation and supervision side and is completely separate to the rest of the organisation. We would never know anything about any investigation of the details of it. It’s business as usual as far as Milford is concerned from our perspective.”