I suspect the issue is they still need cash for 1. dividends 2. Further dilution, er acquisition. They have some put away for the near term dividends. But you can see the negative feedback loop if they cant make those payments/acquisitions. Having a huge hole in the books wont help for raising cash through lending, or asset sales realizing the loss.

Re: 10% specifically, i havent checked but Im guessing thats a floor on their cost basis for a bunch of holdings going negative.