[tyre]

They don't stop people from selling. Circuit breakers are useful for one-time flukes (e.g. Flash Crash) but for sustained downturns they can actually make things worse.

If you think you _may_ want to sell at all tomorrow but also think a circuit breaker could trigger, you're going to sell first thing in the morning. So will everyone else.

The circuit breaker can actually trigger a worse panic as investors all try to squeeze in sell orders at once. This triggers the circuit breaker, confirming everyone's fears, and starts again the next day.

[fleitz]

It makes it worse when they say they are propping up the market, if the market is at a relative peak and daddy warbucks shows up saying he'll buy anything no matter the cost, of course everyone is going to get out while the getting is good.