I'd been part of the received wisdom that any act of US default would set off a devastating chain reaction of bankruptcies that would provoke a second global financial crisis. But David Bloom, chief currency strategist at HSBC, has convinced me that dollar hegemony might perversely act in the opposite way, at least initially.
Unlike a generalised credit event, where all instruments default at the same time, the US would initially engage in a series of little, self contained defaults, or "selective defaults", whose individual impact would probably not be that great.
Each bond has a life and coupon of its own. The missed coupon payment might therefore be regarded as not so bad – especially as this is a case of "won't pay", rather than "can't pay".
Markets see such defaults differently, with missed payments expected to be made up eventually once a political resolution is found. It's also very likely that the Federal Reserve would attempt to counter the damage in financial markets with more QE, buying up the Treasuries that investors dumped.
Furthermore, the financial uncertainty created by default would likely drive investors towards past safe havens of choice – in particular, US dollar assets. Alternative safe havens, such as Japan and Switzerland, have been rendered defunct by central bank money printing. Ironically, emerging markets are likely be more damaged by default than the US itself, with further capital flight.
Such is the degree of "exorbitant privilege" enjoyed by the dollar that it might therefore be the first currency in history to see an asset price rally on the back of a default. However, if there were repeated selective defaults, a second, less benign phase would eventually set in. Spooked markets would begin to sell off the dollar.
The consequent stronger euro and pound would have powerfully deflationary consequences for Europe. Internal demand in the US would also collapse as a result of the wrenching fiscal squeeze that would result from federal government attempts to match expenditures with tax revenues.
Dollar hegemony has long been a destabilising force at the centre of the international monetary system; it's a major part of the sharp build-up in global current account imbalances and cross border capital flows that have been at the heart of so many of the problems in the world economy. The unprecedented accumulation of dollar foreign exchange reserves has in turn caused new challenges for the US, making it more difficult to maintain fiscal and financial stability within its own borders.
Policies that may or may not be good for the US are in all probability bad for everyone else. Loose monetary policy in the US since the crisis began has induced unwanted demand and asset bubbles elsewhere in the world.