Penny stocks, they divide market watchers like no other. Some investors steer clear of these tickers going for less than $5 apiece, as poor fundamentals or overwhelming headwinds could be keeping them down in the dumps.On the other hand, penny stocks lure the more risk-tolerant. Not only does the bargain price tag mean you get more bang for your buck, but also even minor share price appreciation can yield huge percentage gains. The implication? Major returns for investors.Based on the above, weeding out the long-term underperformers from the penny stocks going for gold can pose a significant challenge. In this case, the activity of legendary stock pickers can provide some inspiration. Among these Wall Street titans is Israel “Izzy” Englander. Englander serves as the Chairman, CEO and Co-Chief Investment Officer of Millennium Management, the hedge fund he founded in 1989. Speaking to his impressive track record, he took the $35 million the fund was started with and grew it into $73 billion in assets under management. With this in mind, we used TipRanks’ database to find out what the analyst community has to say about three penny stocks that Englander’s fund snapped up recently. As it turns out, each ticker has received only Buy ratings. Not to mention substantial upside potential is also on the table.Kindred Biosciences (KIN)Hoping to bring innovative biologics to veterinary medicine, Kindred Biosciences believes pets deserve the same kinds of safe and effective medicines that humans enjoy. At $3.78, Wall Street pros believe its share price could reflect the ideal entry point given everything the company has going for it.Englander is among the KIN fans. During Q2, Millenium pulled the trigger on 821,752 shares. As for the value of this new position, it comes in at $3,690,000.Also singing the healthcare name’s praises is Cantor analyst Brandon Folkes. “KIN has a pipeline of very good assets with the potential to generate significant value if they are brought to market,” Folkes explained. The analyst points out that there has been a strategy and priority shake-up over the last 12 months, but he believes the company’s “pipeline of novel animal health drugs will drive long-term shareholder value beyond levels reflected in the current stock price.”The company continues to advance its biologics programs, including IL-31 and IL-4R antibodies for canine atopic dermatitis, KIND-030 for parvovirus in dogs and KIND-510a for the control of non-regenerative anemia in cats, together with long-acting versions of certain molecules, “all of which could be best-in-class large-market opportunities,” in Folkes’ opinion.Adding to the good news, Folkes sees its partnerships as helping to unlock value. These partnerships include a manufacturing agreement with Vaxart to manufacture Vaxart’s oral vaccine candidate for COVID-19. Summing it all up, Folkes stated, “With animal health companies trading at 4.5-8.5x estimated 2021 revenue, and with business development playing a significant role in driving long-term growth for these larger animal health companies, we believe KIN’s pipeline offers a unique suite of meaningful revenue opportunities for larger companies, if KIN can deliver on its pipeline’s potential. We believe KIN’s stock remains undervalued at current levels, and as 2020 progresses, we expect pipeline advancements to drive the stock higher.”To this end, Folkes rates KIN an Overweight (i.e. Buy) along with an $11 price target. Should his thesis play out, a potential twelve-month gain of 191% could be in the cards. (To watch Folkes’ track record, click here)Other analysts don’t beg to differ. With 4 Buy ratings and no Holds or Sells, the word on the Street is that KIN is a Strong Buy. The $11.50 average price target is more aggressive than Folkes’ and implies 208% upside potential. (See KIN stock analysis on TipRanks)Agenus Inc. (AGEN)Next up on our list is Agenus, which develops an immuno-oncology portfolio that includes checkpoint antibodies, cell therapies, vaccines and adjuvants. While this name, which changes hands for $4.02 apiece, has stayed relatively under the radar, some believe big things could be on the horizon.During Q2, Millenium made a major purchase. Scooping up 2,339,149 shares, the hedge fund’s new AGEN position is valued at $9,193,000. 5-star analyst Mayank Mamtani, of B.Riley FBR, has also been impressed. On August 6, AGEN provided an update regarding the progress of its pipeline. Its lead programs, AGEN2034 or balstilimab (bali; anti-PD1) and AGEN1884 or zalifrelimab (zali), are on track for separate BLA submissions, both in combination as well as bali as a monotherapy by YE20, in all-comer refractory/relapsed (r/r) cervical cancer.“Of note, within r/r cervical cancer, zali/bali is clinically de-risked and meaningfully differentiated relative to competing approaches in Merck’s Keytruda and/or Iovance’s TIL-based cell therapy; further, we view zali/bali to serve as an effective fast-follower to BMY’s ipi/nivo across several tumor types with pricing optionality a key strategic leverage for AGEN to deploy upon market entry in 2021,” Mamtani explained.On top of this, AGEN1181, its multi T-cell and CTLA-4 engaging antibody which was Fc-engineered to overcome a genetic polymorphism in the CD16 allele, produced a strong result in the Phase 1 trial in MSS r/r endometrial cancer. After there was a CR generated by the AGEN1181 1 mg/kg monotherapy dose, AGEN1181 0.3 mg in combination with zali had a PR with ~80% tumor shrinkage change into a CR, as evidenced by a PET scan.“We are encouraged by AGEN identifying accelerated path to market by pursuing PD-1 refractory melanoma as well as ‘cold’ tumors in MSI-stable endometrial and colorectal cancer, and hepatocellular carcinoma, possibly in Phase 2 single-arm settings, as well as realize full potential longer term in large prevalence tumor types such as NSCLC and prostate cancer. On latter, AGEN’s intent to establish AGEN1181 as preferred checkpoint inhibitor for combination therapy was recently validated by AACR’20 abstract demonstrating synergistic benefit with several therapeutic modalities,” Mamtani added. Bearing all of this in mind, Mamtani rates AGEN a Buy along with an $8 price target, which implies a 99% upside from current levels (To watch Mamtani’s track record, click here)Looking at the consensus breakdown, it has been quiet when it comes to other analyst activity. In the last three months, only 2 analysts have issued ratings. However, as they were both Buys, the word on the Street is that AGEN is a Moderate Buy. (See Agenus stock analysis on TipRanks)Marinus (MRNS)Last but not least is Marinus, which works on neuropsychiatric therapeutics and is considered a leader in orphan epileptic disorders. Currently going for $1.76 apiece, several members of the Street believe that it’s time to get in on the action.Englander is standing squarely with the bulls on this one. The billionaire’s fund bought up 934,155 shares in Q2. Reflecting a new position, the value of the holding lands at $2,373,000.Ahead of a fast-approaching data readout, Oppenheimer analyst Jay Olson is on board. Pivotal Phase 3 Marigold data for ganaxolone (GNX) in CDKL5 Deficiency Disorder (CDD) is scheduled for release any day now. The last patient visit for this trial took place in July, and the primary endpoint is seizure frequency reduction over 17-weeks for GNX versus placebo. “Prior Phase 2 open-label trial data show seizure frequency reduction of -44% at day-28 (N=7) and -54% at 6-months (N=4), suggesting durability, and low discontinuation rate of less than 10% in Phase 3 MARIGOLD suggests favorable tolerability,” Olson commented.However, Olson points out that this data release is being “overshadowed by long-term value drivers.” The first of these is the RSE pivotal Phase 3 trial of GNX, the design and dosing of which was confirmed in the EOP2 FDA meeting. MRNS still expects to kick off the trial in Q3 2020. Olson noted, “We view pivotal Phase 3 design as similar to positive Phase 2 trial while benefiting from longer dosing with 12 hours exposure vs. 8 hours prior. MRNS expects topline data in 1H22.”If that wasn’t enough, MRNS announced that patient screening had begun for the Tuberous sclerosis complex (TSC) Phase 2 trial of GNX, with the topline readout slated for 1Q21 with Allo-S biomarker analysis.Given everything MRNS has going for it, Olson rates the stock an Outperform (i.e. Buy) along with a $6 price target. This suggests that shares could move 237% higher in the next year. (To watch Olson’s track record, click here)It turns out that other analysts also like what they’re seeing. Only Buy ratings, 4 to be exact, have been received in the last three months, so the consensus rating is a Strong Buy. In addition, the $6.50 average price target indicates 263% upside potential. (See Marinus stock analysis on TipRanks)To find good ideas for penny stocks trading at attractive valuations, visit TipRanks’ Best Stocks to Buy, a newly launched tool that unites all of TipRanks’ equity insights.Disclaimer: The opinions expressed in this article are solely those of the featured analysts. The content is intended to be used for informational purposes only. It is very important to do your own analysis before making any investment.