In the following paper I explore the issue of the dollar as the unofficial reserve currency of the global finance system. I look at arguments for its "resilience" or continued use and how there is an inbuilt mechanism in liberalized capital that tends to reinforce the use of the dollar, and how this is to the advantage of the United States. I then look at the various ways in which the dollar has become increasingly vulnerable as a reserve currency because of the current constitution of the U.S. economy and because of its mutual dependency with China. I also set out how finance and other markets can go into sudden decline because of these vulnerabilities and how the constitution of the markets themselves can exacerbate this. Both of these factors, I argue, are problematic for the system, and provide the basis on which the dollar may ultimately cease to be the unofficial reserve currency.