Who and Why?, page-29

Diversified were a substantial shareholder up until the cap raising to buy the rest of Challenger at the end of July 2016. When the new shares were issued their holding was diluted below 5%.

They should have released the standard notice informing everyone that they were ceasing to be a substantial holder but I can't see one.

As you would be aware, from this point on they could sell down without informing the market. We can't divine too much from the Top 20 in the 2016 annual report. Only that no one held the exact amount that Diversified did in July 2016. Diversified may have their shares held by one of the nominees listed. It would make sense for them to have their shares held by a nominee as it gives them another layer of anonymity from analysis such as this.