For investors who enjoyed the huge run of marijuana stocks last year, the first half of 2017 probably hasn't been as exciting. Several of the largest marijuana stocks haven't performed all that great so far this year.

But how something begins doesn't necessarily dictate how it ends. I think that three marijuana stocks in particular could make you plenty of money in the second half of 2017. Here's why Aurora Cannabis (NYSE:ACB), Canopy Growth Corporation (NASDAQ:CGC), and Insys Therapeutics (NASDAQ:INSY) could be big winners by the time December winds down.

Marijuana buds and pill bottle on top of money

Image source: Getty Images.

Aurora Cannabis

Aurora Cannabis soared more than 300% last year. So far in 2017, however, Aurora's share price has climbed only by a low double-digit percentage. I don't expect the stock to perform like it did in 2016 in the remainder of the year, but there are several reasons to anticipate a strong finish for Aurora in 2017.

The company ranks as one of the largest licensed providers of medical marijuana in Canada. This market continues to expand. As of late June, Aurora had 16,000 active registered patients less than 18 months after its first sale. The company added 3,000 of those patients in May and June alone. If this recent momentum continues (which I think will be the case), Aurora's revenue should increase tremendously in the next few months.

Aurora also stands to benefit from its expansion into the German market. Germany legalized medical marijuana earlier this year, but the country is importing the drug until it can establish a regulatory program for cultivation. That has opened a big market to Canadian marijuana growers in particular. Aurora has jumped on this opportunity by acquiring Pedanios GmbH, a leading German wholesale importer, exporter, and distributor of medical cannabis, a few months ago.

Then there's the potential for Canada to legalize recreational marijuana. Prime Minister Justin Trudeau appears to be committed to making that happen by July 2018. If that target date becomes more solidified over the next few months, expect Aurora Cannabis stock to rise in anticipation of a huge new market opening up in the near future.

Canopy Growth

Pretty much everything stated for Aurora Cannabis also applies for Canopy Growth -- except Canopy Growth is even bigger. Canopy Growth stock more than tripled in value last year but is only up a little so far in 2017. It could be poised for a fantastic finish, though.

Sales are soaring for the Canadian medical marijuana supplier. Canopy Growth reported its fiscal 2017 financial results on June 27. Revenue increased 214% year over year to nearly $40 million. Sales should keep on rocking throughout the rest of 2017.

Canopy Growth made a move into the German market even before the country officially legalized medical marijuana. It acquired Germany-based distributor MedCann GmbH Pharma and Nutraceuticals in November 2016. Canopy was also recognized by the German government as the first North American legal supply source of medical marijuana.

Like Aurora Cannabis, Canopy Growth appears poised to reap the rewards if Canada legalizes recreational marijuana. This legalization seems inevitable, even if it's delayed to give provinces more time to implement.  

Insys Therapeutics

We probably could have included one of the other Canadian medical marijuana growers on the list for the exact same reasons Aurora Cannabis and Canopy Growth should be big winners in the second half of 2017. However, for variety's sake, I instead picked a biotech that develops cannabinoid drugs: Insys Therapeutics.

Unlike Aurora and Canopy Growth, Insys stock performed horribly last year -- plunging nearly 70%. Insys was up close to 60% year to date in May 2017, but gave up most of those gains. I think it could make a big comeback for two primary reasons.

First, in late July Insys finally launched Syndros, its cannabinoid treatment for anorexia associated with weight loss in AIDS patients and nausea and vomiting associated with chemotherapy in cancer patients. The company won regulatory approval for Syndros last year, but had to wait a long time for scheduling by the U.S. Drug Enforcement Agency (DEA). The drug should bolster Insys' financial performance in the second half of this year, particularly in the fourth quarter. 

Second, there are some encouraging signs that sales for Insys' opioid painkiller Subsys could stabilize. The company announced recently that Subsys was being included on the formulary of a large pharmacy benefits manager (PBM) that had excluded the drug in the past. That change took effect in July. In addition, there are some other positive developments for Subsys that could impact sales in 2018. The drug will be the preferred TIRF (transmucosal immediate release Fentanyl) product on the formularies for two top PBMs and one large health insurer next year. 

Half-baked predictions?

I'll be the first to admit that my predictions for these marijuana stocks' second-half performances could be way off if certain events happen. For Aurora Cannabis and Canopy Growth, any big bumps in the road for legalization of recreational marijuana in Canada would take a huge toll on the stocks.

Insys faces several risks that could derail a potential comeback. A massive fine from investigations into its past marketing practices could hurt. So could a weak launch for Syndros or a greater-than-expected loss of sales for Subsys.

Despite these real risks, though, I still think Aurora, Canopy Growth, and Insys could be the marijuana stocks that make investors the most money in the second half of 2017. And 2018 could be even better for all three stocks.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.