Amid the fallout of the General Electric Co. (GE) debacle, a delicate but crucial social contract between shareholders, bondholders, and corporate America is being quietly redrawn.

For a decade since the financial crisis, U.S. companies have piled up debt to fund generous equity buybacks, helping supercharge a fourfold jump in the S&P 500 Index. But as scrutiny on companies' financial health mounts, creditors are seeking to wrestle back control and curb these balance-sheet-be-damned maneuvers.

Already, U.S. companies are curtailing the volume of bonds sold to buy back their own stock—reducing that amount by a third in 2018, based on a Bloomberg data search of transactions detailing use of proceeds. In Europe, where it's more unusual for companies to borrow to redeem stock and profitability has recovered more slowly, issuance is running at an eight-year low.