“Only buy something that you'd be perfectly happy to hold if the market shut down for 10 years,” counselled Warren Buffett.
The London Stock Exchange Group does not want you to take that risk.
It was revealed this week that the company is considering the launch of 24 hour trading on its bourses, marking a big extension from its operating hours of 8am to 4.30pm.
Such a move would extend access for everyone, from late night UK retail traders on their smartphones in Stockport, to early risers in Singapore.
The exchange is said to be assessing the practicalities of implementation, such as regulatory and technological requirements.
Sure, efforts to innovate and grow should be applauded — especially for firms operating in post-Brexit UK. The nine years since the referendum to leave has been no easy ride.
Yet this proposal is seriously misguided.
For one, any risk manager will tell you that round the clock trading runs the risk of illiquidity and therefore outsized price action. Stops can easily be triggered and orders manipulated.
A better starting point would be the abolition, or at least a reduction, of stamp duty. It stands at 0.5% for UK shares compared to 0.3% in France and zero in the US. So much for Singapore on Thames.
More broadly, the proposal also betrays a hint of desperation, especially for the UK with its longstanding productivity problem.
Extending trading hours is not going to solve that problem. The pandemic taught us that it is about working smarter, not for longer.
If the UK wants to have a thriving, bustling equity capital market once again, it needs wider, structural reform that makes investing in it more attractive.
Getting a midnight margin call on AstraZeneca, triggered by a flash boy in Tokyo, is not going to foster that.