In 1991, Midway, Pan Am and America West from the airline industry all entered bankruptcy. (Stretch the period to 14 months and the list includes Continental and TWA.)
Warren Buffett does not like the airline industry at all.
Despite the huge amounts of equity capital that have been invested, overall, the industry has posted a net loss since its birth after Kitty Hawk.
The problem is made worse by the fact that the courts have been encouraging bankrupt carriers to continue operating.
These bankrupt carriers can temporarily charge fares that are below the industry’s costs because they don’t incur the capital costs faced by their solvent peers. These losses are then funded by selling off assets.
The low fares by bankrupt carriers contributes to the toppling of previously-marginal carriers, making it unprofitable (and spelling doom) for everyone.