For the past 15 months, investors have enjoyed a historic bounce-back rally. Following a five-week tumble in the widely followed S&P 500 during the first quarter of 2020, the benchmark index has gained as much as 90% from its lows.

Amazingly, though, bargains still abound -- at least in the eyes of Wall Street.

For each of the following four popular stocks, a Wall Street analyst has issued a 12-month price target that implies nearly 200% upside. That would represent an incredible return, considering how far the market has bounced off of its bottom. Let's take a closer look to see if these high-water price estimates are actually achievable.

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Coinbase: Implied upside of 183%

Even though it's a relatively new publicly traded company, Wall Street analysts wasted little time heaping praise on cryptocurrency exchange Coinbase (NASDAQ:COIN). In particular, analyst Gil Luria at D.A. Davidson increased his firms' price target on the company to $650 a share, which would represent upside of 183% from where the company ended last week. The question is: Can Coinbase achieve such a lofty valuation? 

On one hand, Coinbase ended March with more than 56 million verified users and $223 billion in assets on its platform. For context, that's up 22 million users in a year, with assets ballooning from $17 billion to $223 billion in that time. Not surprisingly, net income also catapulted higher, with the company generating $771 million in profit in Q1 2021, up from $32 million in the prior-year period. 

On the other hand, Coinbase is entirely driven by the hype surrounding Bitcoin and Ethereum. Trading activity has historically risen when these Big Two of crypto are making new highs, whereas revenue falls off like a ton of bricks when cryptocurrencies enter multiyear downtrends. The last time Bitcoin shed more than 80% of its value, Coinbase's sales were nearly halved. Considering that Bitcoin has been nearly cut in half from its high of more than $64,000, the near-term outlook for Coinbase isn't too hot.

What's more, there's virtually no barrier to entry among cryptocurrency exchanges, which means competitors could easily undercut Coinbase's fees. Despite being the premier crypto trading platform for the time being, I don't see this price target as achievable.

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Trulieve Cannabis: Implied upside of 195%

Wall Street has been keeping a close eye on fast-growing marijuana stocks. In particular, Stifel analyst Andrew Partheniou is practically pounding the table on U.S. multistate operator (MSO) Trulieve Cannabis (OTC:TCNNF). After announcing an all-stock deal to acquire MSO Harvest Health & Recreation (OTC:HRVSF), Partheniou upped his firms' price target to $132 Canadian. That works out to a 195% implied gain, when converted to U.S. dollars. 

The most interesting thing about Trulieve is its focus. Whereas most MSOs have chosen to operate in a dozen or more legalized states, Trulieve has devoted almost all of its attention to medical marijuana-legal Florida. As a result, 84 of the company's 90 operational dispensaries are located in the Sunshine State. By blanketing Florida, Trulieve has effectively built up its brand awareness with consumers and delivered 13 consecutive profitable quarters.

The aforementioned big news is the pending merger with Harvest Health. Harvest has a five-state focus, one of which is ironically Florida. Thus, this deal will give Trulieve an even larger share of its home market. But the real crown jewel of this acquisition is Harvest's 15 Arizona dispensaries. Arizona legalized recreational marijuana in November 2020, and Trulieve shouldn't have any trouble duplicating its success in the Grand Canyon State.

While Partheniou's price target might be a bit aggressive, there's plenty of upside potential with Trulieve.

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Root: Implied upside of 180%

Another popular stock that would appear to offer significant upside is new-age insurance company Root (NASDAQ:ROOT). In November, JMP Securities analyst Matthew Carletti slapped a market outperform rating on the company, to go along with a $30 price target. If accurate, Carletti's target implies a cool 180% upside from where Root closed on June 18. 

What makes Root such an intriguing company is its unique approach to pricing policies. Rather than using the same broad-based data for pricing auto insurance policies that the industry has used for decades (credit scores, age, gender, and so on), Root is relying on telematics. It's collecting copious amounts of data from smartphones, which have highly sensitive equipment inside of them (e.g., gyroscope and accelerometer) to help measure factors like G-forces when turning, quick acceleration, and hard braking. By using telematics, Root can effectively price policies based on users' driving habits, and not inefficient broad-based data.

During the first quarter, Root reported a direct accident period loss ratio of 77%. For context, any figure under 100% is a profitably written policy. Two years ago, the company's direct accident period loss ratio was 106%. This would suggest that the company's telematics-based approach is working by pricing auto policies more accurately. 

However, the one thing that could keep Root from achieving Carletti's price target is its quarterly losses. Root is a relatively young company, and it's going to be a while before it has any chance to turn the corner to profitability. A $30 price target is likely too aggressive, but upside from where it closed this past week is warranted.

The hydrogen fuel cell emblem on the trunk of a white sedan.

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Plug Power: Implied upside of 163%

Finally, at least one Wall Street analyst is expecting big things from hydrogen fuel-cell solutions provider Plug Power (NASDAQ:PLUG). Amit Dayal of H.C. Wainwright recently maintained his company's buy rating on Plug, with a price target of $78. This implies up to 163% upside for the company. 

The plain-as-day buy thesis for Plug Power is the pressing push by developed countries to fight climate change by adopting cleaner sources of energy. Any green-energy legislation passed in the U.S. may well include tax credits or incentive for individuals or businesses that utilize fuel-cell technology.

Plug Power also benefited from striking two joint ventures just days apart from each other in January. South Korea's SK Group took a 10% stake in the company and plans to work with Plug to develop fuel-cell vehicles and refilling stations in South Korea. Days later, Plug formed a joint venture with French automaker Renault to target Europe's light commercial vehicle market. Based on these deals, Plug sees its gross billings nearly quadrupling between 2021 and 2024.

The biggest knock against Plug Power is that investors have a tendency to overestimate how quickly next-big-thing technologies will be adopted. This isn't to say fuel-cell technology doesn't have a profitable future, so much as to point out that Plug's growth could be filled with more potholes than are currently in focus. It's something to keep in mind when considering Dayal's lofty price target.

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.