Companies that extract cannabidiol, or CBD, from hemp are expected to prosper in 2019.

Hemp, a species of cannabis plant with a very low concentration of the psychoactive constituent THC, is cultivated for commercial purposes or research in 47 countries, according to New Frontier Data.

On Wednesday, Congress passed farm legislation that includes a provision to legalize the cultivation of hemp in the U.S. The $867 billion farm bill, which is expected to soon be signed into law by President Donald Trump, will enable farmers to grow and sell hemp with the help of USDA crop insurance and grant programs.

Analysts covering the marijuana sector predicted that this important change will significantly boost the hemp-derived CBD market. Cannabis research firm Brightfield Group expects the market to be worth $5.7 billion by next year and $22 billion by 2022, representing a huge increase on the $291 million of sales it registered in 2017, according to The Street.

In a research note, Brightfield provided investors with a ranking of the top 20 hemp-derived CBD firms by market share. Among them were five publicly-traded companies: CW Hemp or Charlotte's Web Holdings (CWEB), CV Sciences Inc. (CVSI), Medical Marijuana Inc. (MJNA), Elixinol LLC (ELLXF) and Isodiol International (ISOL).

According to Brightfield, the sector’s biggest company by market share is Charlotte’s Web. The Colorado-based producer of hemp-based CBD products was engulfed in controversy in 2017 when its founders were accused by the FDA of making claims that couldn't be substantiated. However, since then, the Canadian-listed stock has fallen back into favor with investors after the company reported third-quarter revenue and gross profits growth of 57% and 54%, respectively.

Charlotte’s Web CEO Hess Moallem recently told Bloomberg that the company plans to pursue a listing on a major U.S. exchange if the farm bill passes. Bloomberg also reported that several other companies that extract CBD from hemp, including Vertical Cos., are making similar plans.

“We feel that with the farm bill passing, it opens up the pathway to a formal listing on a U.S. exchange like Nasdaq,” Smoke Wallin, president of distribution, sales and marketing at the Agoura Hills, California-based company said.