Shares of Canadian cannabis producer Aurora Cannabis (NYSE: ACB ) have found themselves in a secular downtrend over the past eight months, dropping from over $10 to less than $4 during that stretch, amid mounting concerns over the cannabis market and pot stock valuations. In the big picture, I think this selloff is overdone. Given its size, production and first-mover advantages, Aurora projects as a long-term winner in the cannabis market. That market will be huge one day. So will Aurora.