"Hochtief's bid for Leighton is being overshadowed by the fact that the offer at $22.15 a share appears to have been leaked last week, the AFR's Chanticleer columnist Tony Boyd writes: Leighton shares soared 15 per cent between close of trading on Wednesday and Friday’s close on turnover that was much higher than normal. Leighton usually trades about 1 million shares a day but 8 million shares were traded on Thursday and Friday. The inevitable investigation by ASIC will focus on the identity of those who bought and sold shares. The situation is made more interesting because about 24 million Leighton shares were sold short. That is about 7 per cent of the issued capital but about 17 per cent of the free float. Hochtief made clear on Monday that it was not buying stock in Leighton last week. It has not bought stock since January. At the same time as making a proportional bid, which is an offer to buy 3 out of 8 shares held, Hochtief is formally abandoning the “informal and non-binding governance principles” that have been in place between Hochtief and Leighton for many years."