Today, the US stock market also declined, and it was only after the opening that the decline began. The CME US stock futures trend before the market opened was still quite good, which indicates that at least Asian and European investors in the main trading hours did not sell off heavily. The US stocks were still rising when the market opened, and then they started to fall all the way down. I'm not sure if it's due to pessimistic expectations about the US government shutdown.

Apart from that, the only other possibility I can think of is the geopolitical conflict between Iran and the US, but it doesn't quite feel right. We'll find out tomorrow. As of now, the House is voting on the funding bill. If it passes, the shutdown will most likely end. If the shutdown is the reason, there should be a rebound after it ends. If not, things could get more complicated.

Below, a pullback around 2167-2118.8 can be used to go long, with a target rebound around 2335-2490.