And then...

...there's Dollar General.

Indeed.
DG was down on the massively up day, along with all sorts of other firms that are seen as being in the business of selling imported goods (tariff exposed) to the US public.
Dollar General, Dollar Tree, but also Walmart, Target, Kohl's, Wayfair, Best Buy, etc. And some "goods" brands that don't manufacture in the US, like Nike.

This market reaction is fairly rational - expecting higher sticker prices and lower volumes is presumably more rational than thinking that non-US suppliers will pay any new US taxes on imports. Though that's a bit first-level thinking. Second level, I imagine there may be some even bigger impacts at some US firms that rely heavily on imported intermediate goods, like the way steel tariffs hammered white goods manufacturers a while back. Third level, a lot of firms (like Berkshire) will be affected by a weaker purchasing power by individuals and the general economic drag and accompanying inflation. If almost everything costs more at checkout, people will buy less stuff. It's a pretty general rule: if you tax anything, the economy will generally see less of it. Somehow people never think of that when introducing payroll taxes with euphemistic names like "pension contribution".

There are exceptions. I wonder if we'll see any Giffen goods. Non-luxury goods that counterintuitively rise in demand when their prices rise, because the buyer's decreasing purchasing power requires people to forego the luxury alternatives and forces them to buy more of the non-luxury alternative. This could happen at a dollar store, where sales tend to rise strongly in the second half of a recession.

Jim