Via a long string of sources starting with Tyler Cowen, here is a chart from Crist Kolder Associates:

What this means, roughly speaking, is that for the past 15 years big companies have been hiring CEOs who were born in 1960 and only 1960, give or take a couple of years. In other words, corporate boards are continuing to hire CEOs from the tail end of the baby boom generation come hell or high water. They simply don’t want to break the age barrier and start hiring Gen Xers.
This will change shortly, of course. There’s no choice. But it says something remarkable that apparently the boards of big corporations are really, really uncomfortable with putting their companies into the hands of Xers. So instead they’ve been hiring older and older CEOs, to the point where today the average CEO is being hired only a few years before they might be expected to retire.
So what, if anything, happens when this finally breaks down and a majority of big companies are finally run by Gen Xers? Beats me. But apparently there are a lot of boomers who really don’t want to find out.