"They are creations of easy credit, beneficiaries of central bank largesse. And now that the era of unconventional monetary policy is over, they’re facing a challenge like never before.They are America’s corporate zombies, companies that aren’t earning enough to cover their interest expenses, let alone turn a profit. From meme-stock favorite AMC Entertainment Holdings Inc. to household names such as American Airlines Group Inc. and Carnival Corp., their ranks have swelled in recent years, comprising roughly a fifth of the country’s 3,000 largest publicly-traded companies and accounting for about $900 billion of debt.Now, some say, their time may be running short.Firms that could once count on virtually unfettered access to the bond and loan markets to stay afloat are being turned away as investors girding for a recession close the spigot to all but the most creditworthy issuers. The fortunate few that can still find willing lenders face significantly higher borrowing costs as the Federal Reserve raises interest rates to tame inflation of more than 8%. With surging input costs poised to eat away at earnings, it’s left a broad swath of corporate America with little margin for error.The end result could be a prolonged stretch of bankruptcies unlike any in recent memory."