Try describing the financial gap between men and women, and 78 cents probably comes to mind. That’s what a woman earns for every dollar a man brings home, and it is publicly noted every year on Equal Pay Day.

But the gender pay gap pales in comparison to a growing challenge for women: the retirement gender gap.

Women’s median IRA account balances are 71 percent as big as men’s and their median defined contribution savings just 66 percent. That savings disparity is just one reason for the yawning financial gap leaving millions of older women in poverty: Nearly 2.9 million women lived in poverty in 2013, more than twice the number of men, according to the National Women’s Law Center