How has the dollar’s reserve currency role evolved?

Traditionally, the country that issues the dominant international reserve currency sells its public debt to the rest of the world to meet global demand for liquid and risk-free assets. Two questions have then arisen about the ability of the United States to continue to play this role: Is the stock of US Treasuries sufficient to meet global demand for risk-free bonds? Will the US succumb to “Triffin’s curse”? The fact that the dollar is the dominant reserve currency leads the United States to build up excessive external debt, which may eventually create an external debt sustainability problem and a crisis where the dollar loses its reserve currency status. But there is now a new question: are US Treasuries still the financial asset that gives the dollar its reserve currency role? One may wonder whether purchases of US equities by the rest of the world are gradually replacing purchases of US Treasuries by the rest of the world: if that is the case, it is global demand for US equities that matters and no longer global demand for risk-free bonds. Indeed, there has been a shift in capital inflows in the United States from Treasuries to equities.