The decision was based on a so-called futility analysis of aducanumab data by an independent monitoring committee that determined the trials had little hope of succeeding.
Brent crude oil futures were at $67.82 per barrel at 0122 GMT, down 4 cents from their last close but within a dollar of the $68.69 per barrel 2019-high marked the day before.
The cut comes after the Supreme Court in January overturned one of several lower court rulings against the U.S. firm for abusing its dominant market position.
The shock of the attacks has led to calls for an immediate tightening of laws to restrict access to some firearms, particularly semi-automatic weapons.
Friday's attack, which Ardern labelled as terrorism, was the worst ever peacetime mass killing in New Zealand and the country had raised its security threat level to the highest.