Somewhat off topic, but I can't seem to find a reliable answer elsewhere. If the USA is a net exporter (or close) why are our prices so sensitive to the open m

Somewhat off topic, but I can't seem to find a reliable answer elsewhere. If the USA is a net exporter (or close) why are our prices so sensitive to the open market price? Yes, I understand some of our oil comes from there. But isn't that offset by what we sell there? I understand The Atlantic's theories. But these don't explain how / why we have so much exposure in the first place. We have our own supply, yes?