[Wohlf]

An exchange having to stop trading and gracefully shut down their systems for a few days doesn't really strike me as a disaster though.

[rchaud]

The NYSE was only closed for 3 business days after 9/11. Uptime is important for listed companies.

[IsTom]

It might be slightly inconvenient to people who want to sell their shares.

[terminalshort]

Not really because there are a lot of stock markets these days.

[ta12653421]

But depending on the setup, often you just cant "sell the one thing at another exchange which you bought earlier at a different exchange", sure this depends on the country/etc.

[terminalshort]

There may be some odd financial instrument that can only be traded on a single exchange, but that's generally not going to be something that is liquid enough for HFT trading anyway. The idea that a stock is listed "on the NYSE" and can only be traded there is a quaint anachronism. e.g. https://help.tradestation.com/10_00/eng/tradestationhelp/rou...