Why there is a buyback explosion

Kostin estimates a 35% increase in share buybacks this year and a 5% pop in 2022. Share buybacks from U.S. companies through April have tallied $484 billion, more than double the pace at this same point last year. It marks the quickest pace of U.S. buyback announcements to kick off a year since 2016 ($400 billion), according to Goldman's research.

"Commentary suggests that the main drivers of this increase are excess cash on balance sheets and positive sentiment on the back of strong financial performance," Kostin says.

S&P 500 companies currently have a record high $2.7 trillion in cash on their balance sheets, according to data from Bloomberg Intelligence.

And to be sure, some of the country's biggest companies are wasting no time in throwing money at buybacks as a means to juice their stock prices further. Stock buybacks have the effect of reducing the number of shares outstanding, which pumps up earnings per share and usually a company's stock price.