Sirtex founder Bruce Gray sells down share holding A decade after he blocked a takeover bid from an unwanted US group, founder of cancer treatment company Sirtex Medical Dr Bruce Gray has sold the bulk of his stake in the company. A block of 7.27 million Sirtex shares was sold at $12 a share late yesterday, a slight discount to the market price. In afternoon trading, Sirtex was trading at $12.32, down 2.1 per cent on the day. The block of shares traded late yesterday is equal to 12.95 per cent of the company's capital, and raised a gross amount of $87.24 million for Dr Gray. Dr Gray has been involved in a lengthy dispute with the board of directors of Sirtex over the way the company has been managed, and he has been gradually selling down his holding over the past six months, taking advantage of an upswing in the Sirtex share price as it prepares for greater penetration of its cancer treatment in offshore markets. In June, Dr Gray sold a 1.1 per cent stake in Sirtex, reducing his holding to 14.9 per cent, with yesterday's sale leaving him with a negligible holding in the company. In 2003, Cephalon offered $4.85 cash a share for Sirtex shares and, after originally entertaining the offer, Dr Gray finally changed his mind and decided not to accept the offer, with the bid failing. Sirtex shares have doubled over the past 12 months as it has begun work on several new clinical trials which, if successful, hold the promise of boosting sales of its cancer treating radioactive spheres significantly. Even though results from some of the trails will not be to hand until late next year, the company has decided to boost capacity to produce its spheres, to prepare for an uplift in sales. Earlier this year, Canadian company Nordion sold its Therasphere's unit to a UK company BTG for $US200 million, with Sirtex valued at $688 million at its present share price. Therasphere, which generated annual revenue of an estimated $US48.5 in 2012, up 14 per cent, is a competitor of Sirtex, although its product is a few years behind Sirtex in its markets. The sale by Dr Gray opens the door for a possible takeover of the company since the only other large holder, fund manager Hunter Hall has also been selling down. It retains an 18.7 per cent stake in Sirtex.