Because markets in the short term are almost a random walk and making the blanket statement that “Walmart stock is down today because Deepseek” was an easy narrative to repeat for media people who cover the stock market.

In reality the world is a highly complex, chaotic, reflexive system, and saying “the entire market moved today because of 12,000,000 factors that randomly aligned” isn’t satisfying enough for people to follow your media channel so they can monetize your eyeballs.