With more states voting to legalize marijuana in some way, a new industry is emerging that is expected to reach $21.8 billion in sales by 2020. What was once seen as a “gateway drug” has become the catalyst for a multi-billion-dollar industry.

The U.S. cannabis market is estimated to be worth $6.7 billion. Canada’s market is estimated to have hit $8 billion.

While the industry is still in its infancy, there is a huge potential for growth in the cannabis market. These five stocks look to be promising in 2018.

1. Cannabis Wheaton

Canada is looking at full marijuana legalization this year, which would make it the first major federally regulated cannabis sector in the world. It’s no surprise that many of the fast-growing cannabis companies are based in Canada.

Among these companies, Cannabis Wheaton (CBW:CA) has seen the quickest growth.

The company provides capital to growers to help them expand their cultivation facilities. In exchange, the company gets minority equity interest as well as a percentage of all of the cannabis produced.

Cannabis Wheaton has relationships with 39 clinics and has access to more than 30,000 marijuana patients.

2. Philip Morris

It’s no surprise that Big Tobacco is delving into the cannabis industry. Cigarette smoking is on the decline, so major tobacco companies are moving in the most obvious direction: marijuana.

In 2016, Philip Morris (PM)PM invested in Israel-based Syqe Medical. It was the second-biggest deal in the cannabis world that year. The company plans to invest $20 million into Syqe.

Philip Morris also owns a patent for a GMO plant with application in the cannabis market.

3. AbbVie Inc.

Pharmaceutical company AbbVie Inc. (ABBV)ABBV already has a cannabis-based drug on the market: Marinol. The FDA-approved drug is designed to alleviate vomiting and nausea in chemotherapy patients. It also helps stimulate appetite in AIDS patients.

The company’s revenues have been increasing over the last four years, and its operating income has also been on the rise. AbbVie Inc. also offers a dividend of 3.8%.

The primary risk with this stock is that the company focuses primarily on the U.S. Negative changes in the domestic market could cause the stock to decline.

4. GW Pharmaceuticals

GW Pharmaceuticals (GWPH)GWPH is one the biggest firms entering the cannabis market, with a value of $3 billion and a strong track record.

In the last few years, the company has developed several new products, including those aimed at infantile spasms, epilepsy, schizophrenia and autism.

But the company’s latest drug is making headlines: Epidiolex. The experimental drug may be the first marijuana-based drug for epilepsy to get federal approval in the U.S. The FDA panel has already ruled that the drug’s benefits outweigh the risks.

The drug has the potential to generate $500 million in sales for GW Pharmaceuticals. The decision on Epidiolex could be a game-changer for the industry.

The company has strong fundamentals and plans to invest £50 million in hiring 70 new staff at its UK-based facilities.

5. Cronos Group Inc.

Listed on the Nasdaq in February 2018, Cronos Group Inc. (CRON)CRON has medical marijuana production and distribution plants across several countries, including Canada, Australia, Israel and Germany.

Cronos has a market cap of $1.042 billion, and shares soared 20% when the company moved from the OTC market to the Nasdaq.