But what if? What if the conventional wisdom is wrong on both fronts? First, the outlook for shares may be rather more resilient than it seems right now for a few reasons. Valuations have been falling for more than a year now. Shares are cheaper than they were. Corporate earnings are still rising, by perhaps 10pc this year and in the next couple of years too. 

And then consider fund flows. Something like six times as much money has gone into bond and money market funds since the financial crisis than has been invested in shares. Even just some of that money seeking better returns in equities would provide significant support.

As for bonds, the case against rests on the unarguable point that inflation and rising interest rates are a killer for fixed income investments. No one disputes that. But what if the futures markets are correct in their belief that the Federal Reserve overestimates its ability to raise rates and keep them high.

Rate futures are telling us that the Fed will go hard and fast this year but within 18 months or so will be bringing interest rates back down to a neutral level of around 2.5pc. This week’s weaker than expected core US inflation, excluding food and energy, points that way.

With 10-year yields already at 2.7pc, perhaps the pain will soon be over for fixed income investors. If yields rise any further, say to 3pc, an investor is likely to think that’s a pretty attractive entry point, coupled with a more or less guaranteed return of capital from a government with a printing press.

And if inflation falls as fast as it has risen, which could easily happen once the year-on-year comparisons become more favourable, that could even represent a positive real return.

So, I wonder whether the death of the 60/40 portfolio, like Mark Twain’s, has been exaggerated. I can accept the case for broader diversification – maybe 50 shares, 30 bonds, 10 alternatives like commodities and gold, 10 cash. But the underlying principle of putting your eggs in more than one basket is alive and well.

Tom Stevenson is an investment director at Fidelity International. The views are his own. He is on Twitter at @tomstevenson63