You're right. That would never happen. But that's not how a sovereign default works. Bond holders look at the price of their bonds. As sovereigns amass more debt, bond holders slowly lose their risk appetite - fear of not getting paid back. Buyers push back from the table > bond prices drop > yields jump sharply > causing interest on rolled over debt to surge > which further results in more selling. Vicious cycle. Nobody coordinates anything. Debt holders simply look at the price of the debt, see it collapsing and their capital wiped out, much like an underwater stock trade. So they throw in the towel and cut their losses. That's it. Then, next month, country xyz can't make bond payments because interest carry costs on the debt consume half their budget = default. I don't understand why this is so hard to understand?