For more than a year, patient investors have been handsomely rewarded. All three of the market's major indexes have gained between 83% and 106% since hitting the bear-market bottom set on March 23, 2020.

Yet, not all stocks have participated in the rally. Over the trailing year (through April 27, 2021), around 110 stocks with at least a $300 million market cap have declined by 20% (or more). Given the aforementioned big gains in the S&P 500, Dow Jones Industrial Average, and Nasdaq Composite, this represents a huge underperformance.

But according to analysts on Wall Street, some of these underperformers have a good chance to bounce back in a big way over the coming year. Based on consensus one-year price targets, the following three turnaround stocks offer upside ranging from 91% to as much as 104%.

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Sarepta Therapeutics: Implied upside of 91%

Many of the worst-performing equities over the past year are biotech stocks. With investors rolling the dice on future clinical outcomes, trial data announcements can yield wild price swings for drug developers. Shareholders of specialized drug developer Sarepta Therapeutics (SRPT -0.80%) learned this in January when shares of the company were halved in a day. But if Wall Street's one-year price target is correct, Sarepta could recoup most of its losses by gaining 91% from its April 27 close.

Sarepta's bread and butter is its research in treating Duchenne Muscular Dystrophy (DMD). DMD is an incurable disease diagnosed in children that leads to the destruction of muscle and causes premature death. To date, the company has had the U.S. Food and Drug Administration (FDA) approve three of its gene-specific DMD treatments, which are designed to increase the production of dystrophin.

However, the make-or-break treatment in the company's pipeline is SRP-9001. This is an experimental treatment that utilizes an adeno-associated virus to deliver a gene to muscle tissue that "programs" for micro-dystrophin production.  In other words, SRP-9001 would allow the company to treat a much larger percentage of DMD patients.

The Part 1 data release of Study 102 evaluating SRP-9001 in DMD patients aged 4 to 7 is why the stock was halved in January. Although treated participants showed an increase in their North Star Ambulatory Assessment (NSAA) total score, it wasn't statistically significant. Sarepta, however, blamed this disappointment on fitness differences in its patients during the study and expects a much different outcome in the latter half of this study. Part 2 of Study 102 is, therefore, Sarepta's make-or-break DMD moment. 

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Intercept Pharmaceuticals: Implied upside of 97%

If you want even more upside potential, Wall Street would steer you toward small-cap Intercept Pharmaceuticals (ICPT). Among the 4,000-plus securities with at least a $300 million market cap, it holds the distinction of being the absolute worst performer over the trailing year (down 75%). The only solace is that Wall Street's consensus price target would see Intercept gain 97% over the coming year.

Similar to Sarepta, Intercept's future predominantly lies with one indication: nonalcoholic steatohepatitis, or NASH. NASH is a liver disease that affects between 2% and 5% of the U.S. adult population and has no FDA-approved cure. It can lead to fibrosis, liver cancer, and even death. It's been estimated that NASH represents a $35 billion treatment opportunity.

Intercept is at the forefront of that opportunity, but it's not been without its hiccups. Experimental treatment obeticholic acid (OCA) met one of its two co-primary endpoints in the phase 3 Regenerate study -- a statistically significant reduction in liver fibrosis without a worsening in NASH. Only one met endpoint was needed to declare the trial a success.

On the other hand, the highest dose (also the most effective) led to considerably higher instances of pruritus (itching) and trial discontinuation, relative to the placebo. Perhaps unsurprisingly, Intercept received a Complete Response Letter from the FDA following its new drug application to supply additional safety data.

If OCA were to be approved, even for a small subset of the sickest patients, it would represent a greater than $1 billion sales opportunity.

It's also worth noting that OCA is already approved under the brand name Ocaliva as a treatment for primary biliary cholangitis (PBC). With Ocaliva's PBC sales expected to hit at least $325 million in 2021 (nearly half the company's market cap), investors look to be getting a shot at NASH success nearly for free.

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Inovio Pharmaceuticals: Implied upside of 104%

Yet another biotech stock with big-time upside potential, according to Wall Street, is Inovio Pharmaceuticals (INO -5.10%). Shares of the company have been clobbered recently, but are expected to rally by 104% to nearly $15 based on the consensus 12-month price target of analysts.

For much of the past year, the promise and peril of Inovio have rested with its development of a coronavirus disease 2019 (COVID-19) vaccine. The company's candidate, INO-4800, achieved immunological responses in 38 of 38 patients in phase 1 studies and looked to be on track to be among the roughly six or so early contenders to bring a COVID-19 vaccine to market in the United States. 

Unfortunately, Inovio's phase 2 and 3 studies hit a snag. The FDA placed a partial clinical hold on both phases and requested additional information concerning INO-4800 and the company's Cellectra delivery device. Cellectra uses electrical impulses to open pores in cells to allow plasmids to enter. Though the partial hold on the phase 2 study was lifted, the company has yet to run an all-important phase 3 study and may choose to do so outside the United States. To top things off, the U.S. Department of Defense notified Inovio that it would no longer be providing funding for its phase 3 study

There are two very big problems here. First, Inovio is running out of time to become a major player in treating COVID-19. The U.S. vaccination campaign will likely be complete sometime in July, and major players like Johnson & Johnson can produce up to 3 billion doses for the global market this year. As a reminder, J&J's vaccine is a single-dose treatment.

The other potential red flag is Inovio's track record. The company may have an intriguing delivery device in Cellectra, as well as nearly a dozen unique compounds in clinical trials, but it's yet to have the FDA approve any of its experimental treatments in four decades. 

With a number of its studies partnered, it's always possible Inovio could turn itself around. But given its track record, it may be best off avoided.