AA still had a lot of debt, especially compared to its peers. The stock represents just the equity component of the total firm value, which also includes the debt. For companies that are highly levered, the equity piece will be a lot more volatile.
I don’t know all that much about AA’s capital structure but I imagine it will come down to the decline in earnings caused by Coronavirus and the related impacts and whether that causes AA to violate any debt covenants it has. That’s when it could get ugly although one might think banks/bond holders will be somewhat willing to negotiate temporary waivers in this particular situation.