IOOF have been slowly decreasing their holding ever since they bought 18m odd shares from the Future Fund run by Peter Costello. Not sure if you remember but the Future Fund had a mandate change in regards to risk vs return and decided to sell out of FTA networks. Also about the same time that Peter Costello become chairman of NEC and invested a good amount of his own money in the company.
I think that IOOF was hoping to make a quick dollar from the purchase which they did on some of the shares preceding the purchase but are still going about reducing their holding. The reasons for them selling could be many but as for 'them knowing more than we'll ever know' - that theory has been proven wrong time and time again especially when it comes to smaller cap stocks.
PRT Price at posting:
29.5¢ Sentiment: Buy Disclosure: Held