> Nowhere near as disastrous.
It depends on where you stand. If you're buying shares and don't currently own any, then it makes almost no difference: you buy roughly twice the number of shares at half the previous price for no net difference.
If you already owned shares then you've just had 42% wiped off their value selling them today versus selling them yesterday. Some of those share owners will be 'fat cat bastards who deserve it' (tm), others will be your and my pension funds.