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May 18, 2026
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Why Is Regeneron Pharmaceuticals (REGN) Stock Down -12% Today?

Why Is Regeneron Pharmaceuticals (REGN) Stock Down -12% Today?

Key Takeaways

  • Shares of REGN are trading down approximately 12% in Monday's session following a late-Friday clinical trial disclosure
  • The primary catalyst is the failure of fianlimab, Regeneron's experimental LAG-3 inhibitor, in a pivotal Phase 3 trial for first-line unresectable or metastatic melanoma
  • The fianlimab + Libtayo combination failed to achieve statistical significance on its primary endpoint of progression-free survival compared to Merck's Keytruda
  • A second ongoing Phase 3 trial ("Harmony") comparing the combination against Bristol-Myers Squibb's Opdualag remains active, but offers no near-term regulatory clarity
  • The setback compounds existing pressure on the stock, which was already down more than 11% year-to-date heading into Monday
  • Investors are now closely watching pipeline updates, the Harmony trial readout timeline, and any analyst rating revisions triggered by the news

Opening Summary

Regeneron Pharmaceuticals (REGN) is a leading biopharmaceutical company based in Tarrytown, New York, known for blockbuster drugs including Dupixent (atopic dermatitis, asthma, and other inflammatory conditions), Eylea HD (wet age-related macular degeneration), and Libtayo (certain cancers). REGN shares are trading around $610, down roughly 12% from Friday's closing price of $698.25, following a late-stage clinical trial failure announced after Friday's market close.  The selloff reflects investor disappointment over the collapse of one of the company's most-watched pipeline assets, fianlimab, in a critical first-line oncology indication.

Fianlimab Phase 3 Trial Failure: The Core Catalyst

Regeneron disclosed late Friday that its Phase 3 trial evaluating fianlimab — a LAG-3 checkpoint inhibitor — in combination with Libtayo (cemiplimab) failed to meet its primary endpoint in patients with first-line unresectable locally advanced or metastatic melanoma.  The 1,546-patient trial did show a numeric improvement in median progression-free survival — 11.5 months for the high-dose combination arm versus 6.4 months for the control arm receiving Merck's (MRK) Keytruda — but the result did not reach statistical significance, with a hazard ratio of 0.845 and a p-value of 0.0627.  The low-dose arm performed even worse, with a hazard ratio of 0.931 and a p-value of 0.4661, effectively ruling out that dose level as a therapeutic option in this setting.

What This Means for Regeneron's Pipeline

Fianlimab was considered a meaningful near-to-medium-term growth driver for REGN, especially as the company faces increasing competitive pressures on its legacy Eylea franchise from biosimilar entrants expected in the second half of 2026.  The failure eliminates the regulatory submission pathway for fianlimab in first-line melanoma and forces a reassessment of manufacturing commitments tied to this asset.  No new safety signals emerged in the trial, which preserves some optionality for the compound in other settings, but the absence of near-term regulatory milestones is a clear overhang for the stock.

Broader Competitive and Sector Context

The melanoma immunotherapy landscape is dominated by Merck's Keytruda (MRK) and Bristol-Myers Squibb's (BMY) Opdualag (nivolumab + relatlimab), making it an especially difficult field in which to demonstrate a statistically significant head-to-head advantage.  Regeneron's inability to beat Keytruda adds REGN to a growing list of oncology drug developers that have struggled in this competitive benchmark setting.  The broader biotech sector has faced its own headwinds through the first half of 2026, and this latest development reinforces caution toward companies with binary clinical readouts still outstanding.

Market Context and Trading Activity

Volume in REGN on Monday is tracking well above average levels as investors and institutional sellers respond to the weekend news.  The stock has now decisively broken below both the $698 support level established at Friday's close and several key technical moving average levels that had previously offered a floor.  The move is largely idiosyncratic to Regeneron rather than a reflection of broad market action, as the major indices and the broader biotech ETF space have not shown comparable weakness on the day.

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What Comes Next for REGN

The most significant near-term catalyst for REGN is the ongoing "Harmony" Phase 3 trial, which compares the high-dose fianlimab + Libtayo combination against BMS's Opdualag in the same first-line metastatic melanoma patient population — a readout that investors will now watch more cautiously.  On the commercial side, the potential entry of Eylea 2mg biosimilars in the second half of 2026 represents a structural headwind that will weigh on revenue projections regardless of pipeline outcomes.  Analyst communities will likely issue revised price targets and rating adjustments in the days following this disclosure; the current consensus heading into today was a Buy rating from 21 analysts with an average price target of approximately $853.  Regeneron still carries a fundamentally strong business in Dupixent, which management has outlined a path to $17 billion in annual sales, alongside its growing oncology and rare disease franchises.  However, with a key late-stage asset now removed from the near-term regulatory roadmap, the timeline and degree of pipeline-driven re-rating will be the central question for investors.

Disclaimer

The information on this webpage is provided for general informational and educational purposes only and is not intended as investment advice, a recommendation to purchase or sell any security, or an offer or solicitation related to investments. It does not consider your personal financial situation, goals, or risk profile, and all investing carries inherent risks, including the possibility of losing your entire investment. For more details, please review our full disclaimer.

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Related Ticker: REGN

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Financial writer and active order flow futures trader with a focus on fundamental analysis, macroeconomic factors, and equity research. I make in-depth blogs on stocks and ETFs, bridging the gap between raw market data and real-world trading decisions.


REGN in upward trend: 10-day moving average broke above 50-day moving average on October 26, 2026

The 10-day moving average for REGN crossed bullishly above the 50-day moving average on October 26, 2026. This indicates that the trend has shifted higher and could be considered a buy signal. In 13 of 15 past instances when the 10-day crossed above the 50-day, the stock continued to move higher over the following month. The odds of a continued upward trend are 87%.

Price Prediction Chart

Technical Analysis (Indicators)

Bullish Trend Analysis

The Momentum Indicator moved above the 0 level on October 12, 2026. You may want to consider a long position or call options on REGN as a result. In 56 of 92 past instances where the momentum indicator moved above 0, the stock continued to climb. The odds of a continued upward trend are 61%.

The Moving Average Convergence Divergence (MACD) for REGN just turned positive on October 14, 2026. Looking at past instances where REGN's MACD turned positive, the stock continued to rise in 31 of 50 cases over the following month. The odds of a continued upward trend are 62%.

REGN moved above its 50-day moving average on October 20, 2026 date and that indicates a change from a downward trend to an upward trend.

Following a +17.40% 3-day Advance, the price is estimated to grow further. Considering data from situations where REGN advanced for three days, in 202 of 314 cases, the price rose further within the following month. The odds of a continued upward trend are 64%.

The Aroon Indicator entered an Uptrend today. In 186 of 268 cases where REGN Aroon's Indicator entered an Uptrend, the price rose further within the following month. The odds of a continued Uptrend are 69%.

Bearish Trend Analysis

The RSI Indicator has been in the overbought zone for 1 day. Expect a price pull-back in the near future.

The Stochastic Oscillator demonstrated that the ticker has stayed in the overbought zone for 13 days. The longer the ticker stays in the overbought zone, the sooner a price pull-back is expected.

Following a 3-day decline, the stock is projected to fall further. Considering past instances where REGN declined for three days, the price rose further in 50 of 62 cases within the following month. The odds of a continued downward trend are 56%.

REGN broke above its upper Bollinger Band on October 30, 2026. This could be a sign that the stock is set to drop as the stock moves back below the upper band and toward the middle band. You may want to consider selling the stock or exploring put options.

Fundamental Analysis (Ratings)

The Tickeron Price Growth Rating for this company is 5 (best 1 - 100 worst), indicating outstanding price growth. REGN’s price grows at a higher rate over the last 12 months as compared to S&P 500 index constituents.

The Tickeron PE Growth Rating for this company is 9 (best 1 - 100 worst), pointing to outstanding earnings growth. The PE Growth rating is based on a comparative analysis of stock PE ratio increase over the last 12 months compared against S&P 500 index constituents.

The Tickeron Seasonality Score of 50 (best 1 - 100 worst) indicates that the company is fair valued in the industry. The Tickeron Seasonality score describes the variance of predictable price changes around the same period every calendar year. These changes can be tied to a specific month, quarter, holiday or vacation period, as well as a meteorological or growing season.

The Tickeron SMR rating for this company is 59 (best 1 - 100 worst), indicating strong sales and a profitable business model. SMR (Sales, Margin, Return on Equity) rating is based on comparative analysis of weighted Sales, Income Margin and Return on Equity values compared against S&P 500 index constituents. The weighted SMR value is a proprietary formula developed by Tickeron and represents an overall profitability measure for a stock.

The Tickeron Profit vs. Risk Rating rating for this company is 63 (best 1 - 100 worst), indicating well-balanced risk and returns. The average Profit vs. Risk Rating rating for the industry is 94, placing this stock slightly better than average.

The Tickeron Valuation Rating of 88 (best 1 - 100 worst) indicates that the company is significantly overvalued in the industry. This rating compares market capitalization estimated by our proprietary formula with the current market capitalization. This rating is based on the following metrics, as compared to industry averages: P/B Ratio (3.121) is normal, around the industry mean (3.104). P/E Ratio (22.958) is within average values for comparable stocks, (-0.958). Projected Growth (PEG Ratio) (1.238) is also within normal values, averaging (9.059). Dividend Yield (0.004) settles around the average of (129.907) among similar stocks. P/S Ratio (5.339) is also within normal values, averaging (439.647).

Notable companies

The most notable companies in this group are Regeneron Pharmaceuticals (NASDAQ:REGN), Moderna (NASDAQ:MRNA), Incyte Corp (NASDAQ:INCY), Exelixis (NASDAQ:EXEL), Arrowhead Pharmaceuticals (NASDAQ:ARWR), Sarepta Therapeutics (NASDAQ:SRPT), Novavax (NASDAQ:NVAX), Nektar Therapeutics (NASDAQ:NKTR), Inovio Pharmaceuticals (NASDAQ:INO), Cel-Sci Corp (ASE:CVM).

Industry description

Biotechnology involves genetic or protein engineering to produce medicines/therapies for treating and preventing ailments. The industry also provides crucial ingredients for diagnostics. This multi-billion-dollar industry is heavily focused on research and development, as companies attempt to continually come up with cutting-edge solutions for health. New discoveries for the treatment of diseases provide opportunities for growth for a company in this industry. Discoveries, however, must pass the regulatory approval from the U.S. Food and Drug Administration (FDA) before they can make it to markets. Amgen Inc., Gilead Sciences, Inc. and Celgene Corporation are examples of companies in this industry.

Market Cap

The average market capitalization across the Biotechnology Industry is 2.19B. The market cap for tickers in the group ranges from 58 to 140.2B. VRTX holds the highest valuation in this group at 140.2B. The lowest valued company is SEELQ at 58.

High and low price notable news

The average weekly price growth across all stocks in the Biotechnology Industry was -2%. For the same Industry, the average monthly price growth was -12%, and the average quarterly price growth was -17%. INO experienced the highest price growth at 117%, while ABOS experienced the biggest fall at -89%.

Volume

The average weekly volume growth across all stocks in the Biotechnology Industry was 28%. For the same stocks of the Industry, the average monthly volume growth was 53% and the average quarterly volume growth was -18%

Fundamental Analysis Ratings

The average fundamental analysis ratings, where 1 is best and 100 is worst, are as follows

Valuation Rating: 50
P/E Growth Rating: 44
Price Growth Rating: 66
SMR Rating: 93
Profit Risk Rating: 93
Seasonality Score: -3 (-100 ... +100)
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General Information

a developer of medicines for the treatment of serious medical conditions

Industry Biotechnology

Industry
Biotechnology
Address
777 Old Saw Mill River Road
Phone
+1 914 847-7000
Employees
15410
Web
https://www.regeneron.com
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Why Is Regeneron Pharmaceuticals (REGN) Stock Down -12% Today?