Here, courtesy of Deutsche Bank (via ZeroHedge), is the answer:
In case it is unclear just what the chart above shows, here is DB's explanation: "buyback announcements have surged with February ($98bn) posting the largest monthly tally on record. The pace of actual buybacks tends to closely follow that of announcements."
Aka: lots and lots of buybacks.... but apparently not enough (as despite record corporate buying...net buying is starting to wane...)
2014 saw record share repurchases by companies, many at record valuations. Still, even more went beyond using their own earnings as many also took advantage of cheap money loans thanks to low interest rates to repurchase even more shares. Due to this, the net outstanding shares are shrinking, earnings ratios based on profits vs. outstanding shares are misleading, and corporate debt continues rising.