The author is an FT contributing editor

This week the US is once more negotiating with itself to ensure the federal authorities can proceed borrowing. The stakes are acquainted. And but this time there appears to be extra concern that the greenback itself is in danger — that everybody else, lengthy annoyed with the US foreign money, would possibly take the possibility to cease utilizing it.

The issue with that argument is that there isn’t a such factor as the greenback. There are lots of totally different sorts of {dollars}, every with its personal qualities. No financial regime lasts eternally. However financial regimes aren’t collective delusions, both. {Dollars} is not going to all immediately blow away like smoke if Argentina begins pricing soyabeans in renminbi. Every sort of greenback has its personal worth, and we needs to be exact about which of them are at risk.

Usually after we speak about a foreign money we really imply financial institution deposits. Greenback energy is a measure of the need amongst foreign money merchants to swap deposits in another nation for deposits within the US. The Federal Deposit Insurance coverage Company has made it clear via repeated crises that it’s going to not let any deposits fail, interval.

There is no such thing as a different foreign money with something just like the FDIC’s express assure of $250,000 of deposits, or its implicit assure of evidently just about something. Eurozone financial institution deposits, for instance, are backed solely by nationwide governments, and solely to €100,000. You might not like American financial institution {dollars}, however there isn’t a foreign money that may conceivably exchange them.

There are additionally eurodollars — dollar-denominated deposits at overseas banks. These, too, take pleasure in an nearly express assure from the Federal Reserve, via agreements to briefly swap currencies with overseas central banks in a disaster. No different central financial institution presents something remotely akin to the peace of mind of those swaps. You won’t like this technique, however once more, it’s not clear what might exchange it.

In monetary markets, treasuries perform as {dollars} — they aren’t simply denominated in {dollars}, they’re {dollars}. If the federal authorities begins to overlook funds, the worth of successive runs of treasuries would possibly dip under par. That, in flip, would eat away on the market values of even accountable asset portfolios. It will be dangerous. Treasury {dollars} are in danger.

Beginning at the least with the Financial institution of England’s constitution in 1694, nevertheless, sovereign debt has remained the bedrock of the worldwide monetary system. You might not like this technique — I’ve some questions on it myself — however it’s the one now we have. And right here, sheer quantity is an under-appreciated energy of the treasury greenback.

People consider treasuries as debt, and measure them as a proportion of gross home product, to allow them to argue about what sort of debt load could be sustainable. However as Michael Pettis factors out, everybody else on the earth thinks of treasury {dollars} as belongings, and no different nation has been prepared and capable of produce sovereign debt belongings at something near America’s quantity.

Add up native and federal authorities borrowing and America had pushed $26.9tn in sovereign debt belongings into international monetary markets by September of 2022, based on the latest comparative information from the Financial institution for Worldwide Settlements. (Sure, I do know the Fed additionally holds treasuries.) China and Japan come subsequent, with simply over $8tn every in sovereign belongings in their very own currencies. Only a few different international locations even measure their sovereign debt in trillions.

We consider America’s potential to borrow within the mighty greenback as a privilege, however it’s potential the alternative is simply as true. America’s enthusiastic willingness to borrow helps make treasury {dollars} mighty. You might not want to maintain treasuries in your portfolio. That’s high quality, however what else are you going to carry?

All of those {dollars}, collectively, assist clarify the “invoice of lading” greenback — shipments of products overseas, priced in {dollars}. Conventional foreign money theories argued that items had been priced within the currencies of the place they had been coming from or going to. Newer work has identified that exporters choose dominant currencies, as a result of secure costs are extra vital than sovereign foreign money benefit.

Greenback costs on payments of lading are secure, in flip, due to all of these different kinds of {dollars}. You may imagine that oil priced in {dollars} is only a product of American plane carriers, however the petrodollar alone doesn’t clarify the worldwide proof of dominant currencies.

There are lots of causes to be sceptical of whether or not robust {dollars} are good for America. All these treasury gross sales don’t appear to have paid for a lot productive funding, simply periodic tax cuts and stimulus programmes. However you don’t have to love all of those {dollars} to see that it’s in no way clear what the opposite decisions are.