Speaking at a conference hosted by the Bank of France, Fink said a failure to generate decent returns meant savers were not making enough gains to support themselves in retirement.

"This gap we estimate of having all this money in the short-term area is about a trillion dollars in terms of what (savers) need to invest and support themselves in retirement," Fink said.

"In our view that is why we are seeing a flattening of the yield curve, and in fact we may see an inverted yield curve in the future if we don't start seeing some recognition in terms of the short end for savers."

(Reporting by Leigh Thomas and David Milliken, writing by Andy Bruc; editing by William Schomberg)