What is Stock?Stock is the value of the company that a person can buy shares to own a percentage. `Stock is sold by shares, which are the smallest units of ownership in the company. The shares’ cost can vary based on several things like the size of the company, popularity, or demand for their product or service, projection of popularity or demand.Which companies are leading the cannabis game?Tilray- is a Canadian pharmaceutical and cannabis company that operates all over the world. The shares of Tilray are about $15 each, which is relatively reasonable, but the insecurity of the companies' share value makes it a risk on gained returns. Canopy Growth is another Canadian company formerly known as Tweed. Canopy is a larger company, and that share value reflects that coming in around $20 each.Cronos is another Company out of Canada the is proving that cannabis stock’s growth is not matching projections. . Then there is Aurora Cannabis, with shares at less than $2 a piece. This is an excellent company to get some practice with.Top three companies for January 2020 cannabis stock:Aphria Inc (TSX: APHA) (NYSE: APHA)— showing a high level of transparency Cresco Labs (CSE: CL) (OTCQX: CRLBF)— possible merger with Origin House (CSE: OH) (OTCQX: ORHOF) Canopy Growth Corporation (TSX: WEED) (NYSE: CGC)— high levels of expansion ability and franchising Companies to add to your Portfolio watch list:Aleafia Health (ALEF.TO) (ALEAF)PharmaCielo (PCLO.V) (PHCEF)Namaste Technologies (N.V) (NXTTF)ManifestSevenCanopy Growth Corp.