If this is the case, then an acquisition to prevent a competitor from going bankrupt should generally not be anti-competitive? Since, they would no longer be your competition anyways?
It could be seen as pro consumer, but it also could be seen as anti competitive. Spirit going under would open up space for a new competitor to potentially move in.
An analogy would be two competing gas stations at a very busy intersection with no plots nearby to build more stations. Just by existing they either drive each other down on price or collude on it. One going under means a new station could exist, but one buying the other guarantees prices do not go down.
An analogy would be two competing gas stations at a very busy intersection with no plots nearby to build more stations. Just by existing they either drive each other down on price or collude on it. One going under means a new station could exist, but one buying the other guarantees prices do not go down.