For American Airlines, the nation’s largest airline, the mid to late 2010s were what the Bible calls “years of plenty.”

In 2014, having reduced competition through mergers and raised billions of dollars in new baggage-fee revenue, American began reaching stunning levels of financial success. In 2015, it posted a $7.6 billion profit — compared, for example, to profits of about $500 million in 2007 and less than $250 million in 2006. It would continue to earn billions in profit annually for the rest of the decade. “I don’t think we’re ever going to lose money again,” the company’s chief executive, Doug Parker, said in 2017.

There are plenty of things American could have done with all that money. It could have stored up its cash reserves for a future crisis, knowing that airlines regularly cycle through booms and busts. It might have tried to decisively settle its continuing contract disputes with pilots, flight attendants and mechanics. It might have invested heavily in better service quality to try to repair its longstanding reputation as the worst of the major carriers.

Instead, American blew most of its cash on a stock buyback spree. From 2014 to 2020, in an attempt to increase its earnings per share, American spent more than $15 billion buying back its own stock. It managed, despite the risk of the proverbial rainy day, to shrink its cash reserves. At the same time it was blowing cash on buybacks, American also began to borrow heavily to finance the purchase of new planes and the retrofitting of old planes to pack in more seats. As early as 2017 analysts warned of a risk of default should the economy deteriorate, but American kept borrowing. It has now accumulated a debt of nearly $30 billion, nearly five times the company’s current market value.