A ripple of anxiety ran through Wall Street on Sept. 9 when Jay Clayton, chairman of the SEC, warned that corporate debt now stands at $11 trillion, half the annual gross domestic product of the United States. "Should we be cognizant of the growth in corporate debt, who holds that debt and the potential ramifications for our markets and our economy?" Clayton asked. "Of course we should."

His warning was timely for Hollywood, coming just a couple of weeks before Endeavor Group Holdings CEO Ari Emanuel pulled the plug Sept. 26 on an initial public offering that investors had regarded warily because of his company's staggering debt of $4.6 billion.

Clayton's comment also came within hours of activist investor Elliott Management's disclosure that it had upped its stake in AT&T — initiated with the goal of reversing an acquisitions strategy that has led the telecom giant to borrow massively in order to purchase assets such as DirecTV, which it obtained for $67.1 billion (including debt) in 2015; and WarnerMedia, which it bought for $85 billion in 2018.