United Auto Workers President Dennis Williams, whose union indirectly controls the largest single block of General Motors Co shares, told Reuters an investor group’s proposal that GM buy back $8b of its stock is premature, and the amount too high for the company’s long-term health. An investment firm controlled by Harry Wilson, a former member of the US government task force that restructured GM through bankruptcy in 2009, together with four other hedge funds, is urging it to return part of its roughly $25b cash trove to shareholders. Williams, who said he met Tuesday with Harry Wilson to discuss the proposal, left open the possibility that he could endorse a smaller share repurchase.