Iress' 43¢ per share all-cash takeover offer for fund services business OneVue looks likely to be blocked at an October 9 shareholder vote if Alex Waislitz's Thorney Investments votes against the deal, as flagged.

It requires the approval of 75 per cent of shareholders who cast a vote. It's unlikely all shareholders will. Which means Waislitz's 18.5 per cent stake is, on its own, almost certainly enough to scuttle the deal.