The surge of capital into Canada’s nascent marijuana industry has sent stock prices soaring – and brought warnings it’s a bubble that could soon burst. The value of 26 marijuana stocks listed in Canada has swelled to almost $4-billion from close to nothing in the past two years, as investors rushed to bet on the country’s move toward legalizing recreational use. While investor optimism is being fueled by analysts’ estimates that there could be about 3.8 million recreational marijuana users in Canada by 2021 and billions in sales, there’s mounting concern companies are overvalued. (See also: Canada’s reefer madness reaches new heights as rivals merge)