Check out their balance sheet. It’s already at zero! They already have been spending so much on buybacks (9B a year, ~eq to net income) that there isn’t any equity left in the company since their liabilities have exploded.

On a side note check a lot of large companies today, corporate debt has gone crazy due to buybacks. They’ve converted any stockholder equity remaining into debt, especially after tax cuts and low interest rates. In a bankruptcy, bond holders get paid first.