In the first two chapters of this dissertation, I explore the potential for sovereign debt markets to experience a new type of dynamic lender coordination problem in sovereign debt markets that I call a dynamic panic. During a dynamic panic, expectations of future negative investor sentiments reduce the willingness of the sovereign to repay in the future and thus translate to negative investor sentiments today. I find conditions under which such sentiment dynamics can be active and document their presence in standard models. When the debt is of longer maturity I show that such panics resemble the recent Eurozone crisis, and so I explore policy implications in this environment. I find that interest rate ceilings are an ineffective policy too...