The core promise of the US retirement system is security, but for the vast majority of savers, that promise is failing under the pressure of pervasive fear and volatile markets. That's according to Mike Downing, co-president of Athene USA and COO of Athene Holding, who said the financial fragility of the average retiree means their hard-earned nest egg is far more vulnerable than they realize. "It's a real fear. It's well over half [who] fear running out of money. It's about 64%," Downing told Yahoo Fin ...