If there's one thing we've learned about the marijuana industry over the past couple of years, it's that it's dynamic. With growth prospects for the industry skyrocketing, cannabis stocks have continued to evolve their businesses to take advantage of the changing marijuana landscape.

One of the many ways we've seen this evolution take place is through mergers, acquisitions, and investments, which have really picked up in the cannabis space since the beginning of 2018. With plenty of market share up for grabs, well-positioned and/or cash-rich direct and ancillary players have begun making moves to nab their piece of the fast-growing green rush.

Although this list is bound to change as the industry matures, here are the five biggest cannabis deals we've witnessed to date.

A handful of cannabis buds lying atop a messy pile of cash bills.

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1. Constellation Brands makes a $4 billion equity investment into Canopy Growth

Barring the acquisition of one of the largest marijuana stocks in the world by market cap, Modelo and Corona beer maker Constellation Brands' (NYSE:STZ) $4 billion equity investment into Canopy Growth (NYSE:CGC) is likely to remain the largest cannabis deal for some time to come.

When Constellation Brands made its $4 billion investment into Canopy Growth in August 2018, giving it a 37% equity stake in the company, it actually marked the third time that it had directly or indirectly invested in Canopy. In October 2017, Constellation invested $190 million into Canopy for a 9.9% stake in the company. Then, in June 2018, it acquired a third of Canopy's 600 million Canadian dollar convertible note offering. Inclusive of these notes, and the warrants Constellation Brands received as part of its equity investment, it could up its stake in Canopy Growth to as high as 56% if everything were exercised.

Constellation's management team has made it clear that cannabis is a logical step for a company involved in the alcohol beverage space. With nonalcoholic cannabis-infused beverages set to launch by mid-December in Canada, Constellation is hoping to see the fruits of its investment really begin to pay off.

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2. Canopy Growth agrees to acquire Acreage Holdings for $3.4 billion on a contingent-rights basis

Unlike the largest deal, which was completed in November 2018, the second-biggest deal in history isn't even guaranteed to go to completion.

In mid-April, Canopy Growth agreed to acquire U.S. multistate dispensary operator Acreage Holdings (OTC:ACRGF) for $3.4 billion on a contingent-rights basis. The contingency being that the U.S. federal government has to legalize marijuana before the deal becomes official. Nevertheless, the deal involved a $300 million upfront payout (working out to $2.55 per share) to Acreage shareholders, assuming they approved the combination (which they have). The remainder of the deal will be paid for by issuing Canopy Growth stock, if and when the U.S. federal government changes its tune. Canopy's offer stands for 90 months, providing a 7.5-year runway to make progress in the United States on cannabis.

The allure of Acreage Holdings for Canopy is that it has retail, cultivation, and/or processing licenses in more states (20) than any other publicly traded multistate operator, at least on a pro forma basis. It's also among the top five in terms of retail licenses held, with well over seven dozen. Buying Acreage would allow Canopy Growth to slide right into the U.S. market with the infrastructure needed to be a major player... assuming the U.S. federal government changes its mind on marijuana.

Flowering cannabis plants growing in an indoor farm.

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3. Aurora Cannabis acquires MedReleaf for $2 billion

Though it may seem like eons ago, the largest completed acquisition in the marijuana space is Aurora Cannabis' (NYSE:ACB) all-stock purchase of Ontario-based MedReleaf in July 2018 for $2 billion (in today's dollars, when converted from Canadian dollars).

Aurora Cannabis has made no secret that inorganic growth is a big part of its long-term strategy, with more than a dozen acquisitions made since August 2016. However, none was bigger than MedReleaf, which brought established premium brands into Aurora's portfolio, as well as licensed and operational growing facilities that totaled an aggregate of 35,000 kilos a year (now known as Aurora Ridge and Aurora River). There's also Exeter, which is a greenhouse in the process of being retrofit for cannabis production that can yield at least 105,000 kilos of annual output. All told, MedReleaf provided a 140,000-kilo boost to Aurora's estimated annual peak production. 

What's interesting about the MedReleaf acquisition is the land available next to Exeter. Prior to the acquisition by Aurora, MedReleaf executives noted that a facility 1.5 times the size of Exeter could be built in adjacent land that it owned. Considering Aurora's deeper pockets than MedReleaf, it's not out of the question that a facility capable of 150,000 kilos to 200,000 kilos a year of peak output could be built on this land to support domestic or global marijuana demand.

A vape pen next to a vial of liquid and neatly arranged dried cannabis flower.

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4. Altria makes a $1.8 billion equity investment into Cronos Group

The fourth and final of the billion-dollar deals in the marijuana space goes to tobacco giant Altria (NYSE:MO), which announced a $1.8 billion equity investment into Cronos Group (NASDAQ:CRON) in December 2018. The deal closed in mid-March, giving Altria a 45% non-diluted stake in the company.

Similar to the Constellation-Canopy deal above, Altria also received warrants that it has the option to exercise down the line. Should it choose to do so, it could raise more than $1 billion more in additional capital for Cronos Group, as well as up Altria's stake in the company to as much as 55%. With adult smoking rates hitting an all-time low in the United States, Altria has been looking for ways to reignite growth, aside from simply raising the price on its tobacco products each and every year. It believes that cannabis, and more specifically cannabis vapes, could be the answer.

Meanwhile, Cronos Group desperately needed capital, having ended the quarter prior to the deal closing with less than $25 million in cash on hand. As a company focused on the cannabinoid and derivative markets, Cronos now has the capital needed to execute on its long-term business plan. Just this past week it announced the $300 million acquisition of Redwood Holdings in the U.S., which owns the Lord Jones line of cannabidiol (CBD) beauty products.

A large dispensary sign, with a cannabis leaf and the word dispensary written underneath it.

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5. Curaleaf Holdings agrees to acquire Grassroots for $871 million in a cash-and-stock deal

The fifth-largest deal in the marijuana space goes to U.S. multistate dispensary operator Curaleaf Holdings (OTC:CURLF), which recently announced an $871 million cash-and-stock deal to acquire privately held vertically integrated dispensary operator Grassroots.

Now, I know what you might be thinking: "Wait! Didn't Curaleaf agree to buy Cura Partners, the owner of the Select brand of products, for CA$1.27 billion ($961 million) in an all-stock deal?" It sure did. However, the value of the deal has declined significantly since it was announced, given that it was based on Curaleaf trading at CA$13.30 per share in Canada. Today, the value of the 95.6 million share deal is about $749 million, placing it well behind the Grassroots acquisition that involves $75 million in cash, $756 million based on a 30-day weighted-average price for Curaleaf, and $40 million in weighted-average Curaleaf shares prior to closing.  Though Cura Partners' equity holders could be eligible for an earn-out of up to $200 million, based on Curaleaf exceeding certain 2020 sales targets, the Grassroots deal is, for now, bigger.

The deal to acquire Grassroots will expand Curaleaf's reach from 12 states to 19, as well as vault it into the No. 2 spot in terms of retail licenses held at 131. Further, the combined company, assuming the deal goes to completion, will have the most operational retail stores (68), with no other dispensary operator even close.