Why should investors like marijuana stocks? For some, the rationale might be the enormous market potential. For others, it could be simply that many marijuana stocks have soared over the last year or so.

There are plenty of reasons for investors to like three marijuana stocks in particular -- GW Pharmaceuticals (NASDAQ: GWPH), Insys Therapeutics (NASDAQ: INSY), and Aphria (NASDAQOTH: APHQF). In fact, there are at least 661 million reasons. That's the amount of cash in U.S. dollars that the three companies have combined. Here's why the cash stockpiles held by GW, Insys, and Apria are important.

GW Pharmaceuticals: Enough money to launch Epidiolex

At the end of the first quarter, GW Pharmaceuticals reported cash and cash equivalents totaling $383.9 million. A large chunk of that amount (roughly $290 million) was raised in July 2016 through a public stock offering.

This cash position is critical for GW Pharmaceuticals, because the biotech remains unprofitable. GW posted a loss in the first quarter of more than $43 million. That means the company must continue to pull from its cash to fund operations. The good news is that GW Pharmaceuticals should be in good shape to make it at least through 2018 without having to raise more money.

Even better news is that the company could have significantly more revenue coming in by the time it needs more cash. GW Pharmaceuticals expects to file for U.S. regulatory approval of cannabinoid epilepsy drug Epidiolex in the second half of this year. Estimates are all over the map for how much revenue Epidiolex might make, with bears projecting peak sales of $300 million and bulls projecting peak sales of $3 billion.  

Insys Therapeutics: Cash to get past Subsys woes

Insys Therapeutics enjoyed a nice cash stockpile of $155.3 million at the end of the first quarter, including cash, cash equivalents, and short-term investments. The company's cash position has deteriorated, though, due to falling sales of opioid pain drug Subsys.

Like GW, though, Insys could have help on the way with a new product. Insys' new product is Syndros, a cannabinoid drug for treating chemically induced nausea and vomiting (CINV) and anorexia associated with weight loss in patients with AIDS. The company won approval from the U.S. Food and Drug Administration (FDA) in July 2016, but had to wait for scheduling by the U.S. Drug Enforcement Agency (DEA). The DEA announced in March 2017 that Syndros would be a schedule II controlled substance. Insys now awaits final labeling from the FDA before it can market the drug.

Insys has great expectations for Syndros. It will be the first liquid form of dronabinol on the market. That gives it several competitive advantages, including ease of adjusting of doses by physicians and faster onset of action. Piper Jaffray thinks Syndros could reach peak annual sales of $300 million to $400 million. Insys' solid cash position should allow the company to plow on despite problems with Subsys to see if Syndros becomes as successful as hoped -- and prove short-sellers wrong about the stock.

Aphria: Cash to expand

Aphria reported $122 million in cash, cash equivalents, and short-term investments at the end of its most-recent quarter. Unlike GW Pharmaceuticals and Insys Therapeutics, Aphria is profitable. The marijuana grower posted earnings of $4.95 million on revenue of $5.12 million last quarter.

So why is Aphria's cash position still important? Aphria is one of less than 40 authorized providers of medical marijuana in Canada. The country is on track to allow legalized use of recreational marijuana by the summer of 2018. That means the potential market for Aphria is about to explode. The company's cash position puts it in great shape to expand.

It wouldn't be surprising to see larger marijuana growers in Canada scoop up smaller players. Aphria acquired CannWay Pharmaceuticals last year in an all-stock transaction. The company probably wishes it could have used cash instead: Aphria's share price is up more than 400% since it bought CannWay. Now, Aphria has plenty of cash and could very well use some of it in anticipation of reaching a much larger market next year.

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Should investors buy these three marijuana stocks just because they have plenty of cash? No. There are lots of other factors to consider, including probable earnings growth, valuation, and competitive dynamics.

Still, though, the fact that GW Pharmaceuticals, Insys Therapeutics, and Aphria have strong cash positions makes them more desirable than they'd otherwise be. Thanks to their cash stockpiles, these three are in better shape for the future than many other marijuana stocks.