Canadian medical marijuana company Aleafia Health Inc. ALEAF, -3.57% ca:alef has been added to the Horizons Marijuana Life Sciences exchange-traded fund HMMJ, -1.70% , the company said Friday. HMMJ is the first and biggest ETF offering exposure to the North American cannabis market with holdings that include Canadian players Aurora Cannabis Inc. acbff ACB, +0.14% and Canopy Growth Corp. CGC, -2.26% . The ETF has gained 37% in 2018 as excitement builds ahead of Canada fully legalizing cannabis on Oct. 17. Aleafia is expecting to reach growing capacity of 38,000 kg of cannabis flower in 2019. The company has 50,000 individual patients using medical marijuana and on Thursday announced a partnership with Cronos Group Corp. on a study of the substance as a treatment for insomnia. Shares have gained 193% in 2018, while the S&P 500 SPX, +0.29% has gained 9.6%.