NEW YORK (AP) — Reefer Madness has gripped Wall Street. Investors are craving marijuana stocks as Canada prepares to legalize pot next month, leading to giant gains for Canada-based companies listed on U.S. exchanges. Billions of dollars have poured into the stocks in the last few months, and there's a lot of excitement and a ton of green (money, not leaves) flying around as investors consider the kinds of opportunities these companies might have as the marijuana market in Canada grows, along with the possibility that the U.S.