The stock fell after the market opened though. It opened up 8% but settled late in the morning.
However, given no further company news from Etsy on Tuesday, it seems safe to say that Musk’s tweet was the primary catalyst for the stock rally.
This is, of course, absurd. It is also another example of the increasingly short-term nature of the stock market, an example where algorithms can drive prices and individual investors using services like Robinhood are eager to make a quick buck.