Last year was expected to be when marijuana stocks proved their worth to Wall Street. Unfortunately, that's not what happened, and investors suffered through the worst year on record for cannabis stocks.

To our north, regulatory-based supply problems have wreaked havoc and allowed the black market to thrive. Meanwhile, in the U.S., high tax rates have made it very difficult for legal operators to compete with illicit producers. And as the icing on the cake, some of the most prominent names in the marijuana industry could soon face delisting.

While only one of these pot stocks has been officially warned of a possible delisting, all four are currently in precarious positions.

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CannTrust Holdings

The marijuana stock that's likeliest to get the heave-ho from a major U.S. exchange at some point in 2020 is embattled CannTrust Holdings (OTC:CNTT.Q). CannTrust is facing a double whammy in that it closed below the $1 minimum share price for continued listing as of Feb. 12, and also hasn't reported its operating results in more than 10 months. Filing operating results with the Securities and Exchange Commission is a requirement for continued listing on the New York Stock Exchange (NYSE). CannTrust received a noncompliance notice from the NYSE in December.

For those who may recall, CannTrust is the company that announced last July that it had illegally grown marijuana in five unlicensed grow rooms at its flagship Niagara campus for a period of six months (October 2018 to March 2019). As a result, the company had its cultivation and sales licenses suspended by Health Canada in September. It's unclear if or when CannTrust will regain these licenses, meaning the company is unable to generate any revenue at the moment.

Just as concerning, with CannTrust having not reported its financials in more than 10 months, investors have no clue what sort of cash the company is currently sitting on. Yes, not being able to plant and sell cannabis will lead to lower costs, as will the 140 layoffs the company announced during the fourth quarter of 2019. But without an accurate look at its finances, CannTrust's share price could sink further.

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HEXO

Quebec-based HEXO (NYSE:HEXO) also finds itself in some trouble. Despite its $355 million market cap, HEXO ended Feb. 12 at just $1.25 per share, which is only $0.25 away from breaching the minimum required price to maintain listing on the NYSE. Understandably, companies can and often do appeal delisting notices that are based on their share price. But if HEXO's share price were to fall much more, it'd be squarely in the crosshairs of the NYSE.

HEXO's fall from grace had nothing to do with fraud, as was the case with CannTrust, and everything to do with Canada's aforementioned supply problems. Even signing the largest wholesale cannabis supply deal in history with its home province of Quebec couldn't prepare HEXO and its peers for the licensing issues that ensued in 2019. Between shortages and supply bottlenecks, HEXO has struggled to get product in front of its customers.

Unfortunately, this is also a pot stock whose investors appear to have lost faith in management. Following one too many positive projections that simply didn't come true, HEXO has cut 200 jobs and idled about a third of its peak production capacity. With CEO Sebastien St-Louis suggesting that his company needs 20% market share throughout Canada to become profitable (a feat no Canadian pot stock might wind up achieving), it's no wonder HEXO's share price has cratered.

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Sundial Growers

Another recent train wreck in the cannabis space that could soon be shown the door is Sundial Growers (NASDAQ:SNDL). Just eight months after its initial public offering on the Nasdaq, Sundial finds itself a mere $0.17 above the minimum $1 share price for continued listing.

Sundials problems can essentially be placed in two camps. First, there have been operational issues tied to Canada's supply problems. This includes the delayed launch of higher-margin derivatives, which only began hitting dispensary shelves in mid-December. Weaker operating results have caused Sundial to rethink its growth strategy as well as to cut costs. In a recent corporate update, Sundial announced plans to save $10 million Canadian to CA$15 million per year. Sundial has also primarily sold marijuana in the wholesale market, which generates lower margins than the retail space.

The second concern is, once again, a lack of trust among investors. Roughly three weeks ago, the company's CEO, Torsten Kuenzlen, abruptly resigned. Before this, Sundial was contending with the fallout from allegedly having had a significant order returned by Zenabis Global due to impurities. Failing to disclose this return resulted in a lawsuit against the company. With little in the way of positives for Sundial, delisting is a very real possibility in 2020.

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Aurora Cannabis

Last but certainly not least, the most popular pot stock in the world, Aurora Cannabis (NYSE:ACB), could find itself booted from the NYSE and back on the over-the-counter exchange if it's not careful. Aurora's share price sank to $1.41 in the after-hours session on Wednesday, Feb. 12, meaning only a $0.41 gap existed between its stock and the minimum share price for continued listing.

Aurora Cannabis has been nothing short of a disaster for 11 months and counting. The company continues to lose money on an operating basis and recently announced a massive overhaul that'll see 500 workers let go, along with its CEO, Terry Booth, who's chosen to resign. Aurora's cost-cutting moves also include halting construction on two of its largest cultivation sites and selling another greenhouse, which will collectively cut its annual run-rate output by about 430,000 kilos per year.

The company's balance sheet remains a mess as well. There are questions as to whether Aurora has enough capital to survive over the long run, and its balance sheet is riddled with goodwill following a number of overpriced acquisitions. While a reverse split may be an option for continued listing (should it come to that), Aurora Cannabis certainly appears to be in trouble.