A default can only happen intentionally, so long as we borrow in our own currency. in 2011, S&P downgraded our sovereign debt from AAA, citing political dysfunction as their rationale. It was a stunning rebuke and one that I think doesn’t get enough attention, but it was basically yawned off by the markets. Truth is, US Treasurys are one of the world’s few risk liquid free assets and whether you rate them AA or AAA, the world financial system needs safe havens. Yes, you can buy debt of other highly rated countries and be basically risk free, but the market for German bunds, for example, is just not as large. You might not be able to sell at a good price when you need to.
A long time ago, I read am pamphlet by a bond market guru who imagined “A world without treasury securities.” His thesis, back in 2000, was that the Clinton surpluses would put an end to 30 year Treasury issuance (it actually had ground to a halt) and that the world financial system would have to look for other sources of safety and liquidity, as well as other benchmarks for managing risk. He thought this would be very disruptive. As it turns out, a recession, followed by 9/11 and deficit spending to covert two long wars brought Treasurys back, and this didn’t happen.
But, if we were to default, you would have similar conditions – Treasurys would no longer be "risk free’ by any stretch and liquidity would drain from the market. This would wildly disrupt global payments while the financial system looked for alternatives (Eurobonds? Japan?) and I would expect major failures of financial institutions. The dollar would lose value, earnings at international companies would be disrupted and we could get a reckoning over whether the dollar can be the world’s reserve currency going forward.
So, what would it make sense to own? I’d say no equities until the carnage is at its worst, and certainly no financial stocks anywhere in the world. There will be a temptation to buy foreign stocks but I think those will get killed, too. Debt instruments, including floating rate debt like leveraged loans or fixed rate corporate bonds will be dicey because nobody will know how to price them.
I do not believe in gold. I think that’s a religion.
But I would seek out hard assets like real estate (but, unleveraged), industrial commodities, and vital infrastructure like toll roads and ports. There might be opportunities in alternative yield like healthcare royalties or equipment leases, but I’d keep it simpler (and cheaper) than that and go for a commodities ETF.
Silver lining: I don’t think the Fed will allow this to happen. Even if they have to break a few laws to do it, I think they will use QE to stave off a technical default by monetizing our debt. If I were at the Fed, I wouldn’t ask permission and would say, “by all means, impeach me later.”
If you think a default is inevitable and want to make money on it happening, the play is to buy credit default swaps on US Treasurys, which will pay off in the event of a default. But the carrying cost is high.