The American retirement crisis is here, said Larry Fink, the man who runs the world's largest money manager.

The CEO, chairman and co-founder of BlackRock, which had $4.3 trillion in assets under management through the end of last year—a number that surpassed the U.S. federal budget for 2014—issued a stark warning to the wave of retirees expected to draw government benefits in the coming decades. Fink believes not enough Americans have prepared for their sunset years, and it will eventually cost them and the government.