The way in which he placed the trades allowed him to have anonymity in many cases, he said.
Warminger is said to be a highly experienced equities trader, having worked in New Zealand and overseas for several global firms and he had autonomy at Milford to buy and sell New Zealand traded equities without adequate oversight, Smith said.
As 31 August, 2014, Warminger had $669 million of assets in several funds under his management, including funds invested through a mandate at the time with the NZ Superannuation Fund.
Warminger could face a penalty of up to a $1 million a trade if any of them breached market manipulation rules, which he has denied.
Milford Asset Management has paid a $1.5 million fine under an agreement with the FMA following a year-long investigation. It also committed to introducing new governance and trading controls as recommended in a PwC review.
Last week Milford played down its role in the case which is only the second market manipulation trial in New Zealand. In a note to clients, Milford said there was likely to be media coverage of the case and that its only role was through background evidence to be provided by executive director Brian Gaynor. It said the issues were not "clear-cut" around how the relevant law applies to trading practices.
Warminger still has a 1.5 percent shareholding in the 13-year-old firm which has more than $3.5 billion of funds under management, mainly through KiwiSaver, and 20,000 clients.