Curious. How do you arrive at the conclusion that this is an 'algo driven sell-off geared to scare the weak hands'? Personally, I've always thought that the type of selling we've seen lately and culiminating today must be driven by something more fundamental than merely algorithms. There must simply be a ton of players selling en masse worldwide. It's not a one day blip, but 10 % off the highs over the course of 14 trading sessions. 10 % down is common on corrections, but the speed of this makes it look and feel more like a crash at this point. For example, the 10.92 % correction in fall 2023 took 65 trading days. Early 2023 was 26 trading days down 9.21 %. We didn't have a single day exceeding 4 % down in 2023. Last time that happened was September 2022. We hit 9.71 % down today on SPX, so maybe it can be a temporary low or even the low, but you get the feeling that this can continue way lower. As for what changed, I often get the feeling that market tops take time to carve out. Like the market's in denial for a while before reality sinks in. The unwinding of the yen carry trade has been cited as a reason. There's also the potential attack on Israel. Uncertainty going into the US elections. Autumn is also the seasonally weakest part of the year. Now, watch this rally to the moon tomorrow! I'm not so sure, though.
FWIW, the major correction in 2022 went as low as 27 % from all time highs. The correction from August/October was around 20 % from the prior swing high. SPX. Who the f''k knows at this point.