BlackRock Inc.'s Laurence D. Fink called negative interest rates "particularly worrying" and potentially counterproductive, as social and political risks contribute to what he described as the most fragile global economy in about a decade.

Nations around the world are leaning too much on extraordinary monetary policies while failing to make key decisions and invest in infrastructure to support long-term growth, Fink, chairman and CEO of the world's biggest asset manager, wrote in an annual letter to shareholders on Sunday. The policies are eroding investors' returns and putting pressure on consumers to cut spending as they prepare for retirement, which may ultimately damage the growth that central banks are trying to spur, he said.

"These actions are severely punishing the world's savers and creating incentives to reach for yield, pushing investors into less liquid asset classes and increased levels of risk, with potentially dangerous financial and economic consequences," Fink said. That and other forces, including geopolitical instability, are creating "a level of fragility in the global economy that we have not seen since the lead-up to the financial crisis."