The IO price is already overlaid on that chart above. The blue/aqua line is the IO price (represented by the 62% FE June IO futures contract) - the price scale is on the left. It's showing the IO price and FEX in lock step until 1pm on the 15th of April where FEX started to push ahead of the IO price (shown by the green circle). This is basically traders who are fully aware of the FEX fundamentals and know that the 4c is about to drop. This would then attract the attention of momentum traders who may know nothing about FEX who then start to pile in.
After the news (shown by the green vertical line) the FEX SP separates even further from the IO price as people who were on the sidelines, waiting for proof of profitability, start to pile in. Also existing holders (like myself) are buying as our confidence has increased with this de-risking event. The price peaks at 38c on the 29th of April and traders start to exit (i.e. those trading the news and those trading momentum). Importantly, the bigger boys are also selling at this point as FEX has moved well beyond their valuation model and they have chosen to not update their valuation model as a result of the 4c. They are waiting for 2 consecutive quarters (or more?) before they do this (they have probably been burnt before - i.e. an operation looks all well and good in the beginning but the cracks start to appear a couple of months later).
By the 6th or 7th of May, depending on whether you use the yellow or red circle, the FEX SP has moved back into lock step with the IO price. As a result I suspect that the ATH of 39.5c was driven more by the huge spike we had in IO at that time than any residual benefit of the 4c.
Obviously there is a lot of speculation in the above paragraphs. It's just my thoughts about the dynamics of what is going on.
(20min delay)