Prothena (LTS:0Y3M) E10: $-3.11 (As of Jun. 2026)

Author: Vera Yuan Vera Yuan
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Director of Data and Quant Analytics at GuruFocus
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Founder & CEO of GuruFocus
Dr. Charlie Tian is the founder and CEO of GuruFocus.com, a leading global investment research platform established in 2004. With a Ph.D. in physics, Dr. Tian transitioned from science to finance, applying a data-driven, disciplined approach to value investing.

LTS:0Y3M Prothena Corp PLC LTS:0Y3M
73 GF Score
Price $8.48
GF Value $12.82
Valuation Possible Value Trap
! 2 Warning Signs
View Full Analysis

What is Prothena E10?

Prothena LTS:0Y3M -4.83% 73 E10 is $-3.11 as of Jun. 2026. GuruFocus rates LTS:0Y3M with a GF Score™ of 73/100 and a GF Value™ of $12.82 (Possible Value Trap). The stock has 2 warning signs investors should review.

E10 is a concept invented by Prof. Robert Shiller, who uses E10 for his Shiller P/E calculation. E10 is the average of the inflation adjusted earnings of a company over the past 10 years.

Prothena's adjusted earnings per share data for the three months ended in Jun. 2026 was $-0.356. Add all the adjusted EPS for the past 10 years together and divide 10 will get our e10, which is $-3.11 for the trailing ten years ended in Jun. 2026.

During the past 3 years, the average E10 Growth Rate was -7.00% per year. Please click Growth Rate Calculation Example (GuruFocus) to see how GuruFocus calculates Wal-Mart Stores Inc (WMT)'s revenue growth rate. You can apply the same method to get the E10 growth rate using E10 data.

During the past 13 years, the highest 3-Year average E10 Growth Rate of Prothena was -7.00% per year. The lowest was -7.10% per year. And the median was -7.05% per year.

As of today (2026-09-16), Prothena's current stock price is $8.48. Prothena's E10 for the quarter that ended in Jun. 2026 was $-3.11. Prothena's Shiller PE Ratio of today is .


Prothena  (LTS:0Y3M) E10 Explanation

If a company grows much fast than inflation, E10 may underestimate the company's earnings power. Shiller PE Ratio can seem to be too high even the actual P/E is low.

For the Shiller P/E, the earnings of the past 10 years are inflation-adjusted and averaged. The result is used for P/E calculation. Since it looks at the average over the last 10 years, the Shiller P/E is also called PE10.

The Shiller P/E was first used by professor Robert Shiller to measure the valuation of the overall market. The same calculation is applied here to individual companies.


Be Aware

Shiller PE Ratio works better for cyclical companies. It gives you a better idea on the company's real earnings power.


Prothena E10 Related Terms


Prothena E10 Historical Data

* Premium members only.

The historical data trend for Prothena's E10 can be seen below:

* For Operating Data section: All numbers are indicated by the unit behind each term and all currency related amount are in USD.
* For other sections: All numbers are in millions except for per share data, ratio, and percentage. All currency related amount are indicated in the company's associated stock exchange currency.

Prothena E10 Chart

Prothena Annual Data
Trend Dec16 Dec17 Dec18 Dec19 Dec20 Dec21 Dec22 Dec23 Dec24 Dec25
E10
Get a 7-Day Free Trial Premium Member Only Premium Member Only -2.56 -2.69 -2.83 -3.06 -3.26

Prothena Quarterly Data
Sep21 Dec21 Mar22 Jun22 Sep22 Dec22 Mar23 Jun23 Sep23 Dec23 Mar24 Jun24 Sep24 Dec24 Mar25 Jun25 Sep25 Dec25 Mar26 Jun26
E10 Get a 7-Day Free Trial Premium Member Only Premium Member Only Premium Member Only Premium Member Only Premium Member Only Premium Member Only Premium Member Only Premium Member Only Premium Member Only Premium Member Only Premium Member Only Premium Member Only -3.36 -3.35 -3.31 -3.20 -3.11

LTS:0Y3M vs EVMN, EDIT, CCCC: E10 Comparison

For the Biotechnology subindustry, Prothena's Shiller PE Ratio, along with its competitors' market caps and Shiller PE Ratio data, can be viewed below:

* Competitive companies are chosen from companies within the same industry, with headquarter located in same country, with closest market capitalization; x-axis shows the market cap, and y-axis shows the term value; the bigger the dot, the larger the market cap. Note that "N/A" values will not show up in the chart.


Prothena Shiller PE Ratio vs Biotechnology Industry

For the Biotechnology industry and Healthcare sector, Prothena's Shiller PE Ratio distribution charts can be found below:

* The bar in red indicates where Prothena's Shiller PE Ratio falls into.


LTS:0Y3M
73GF Score
Prothena Corp PLC LTS:0Y3M
E10 is just one metric. See GF Score™, valuation, warning signs, and more.
View Full Analysis

Prothena E10 Calculation

E10 is a concept invented by Prof. Robert Shiller, who uses E10 for his Shiller P/E calculation. When we calculate the today's Shiller P/E ratio of a stock, we use today's price divided by E10.

What is E10? How do we calculate E10?

E10 is the average of the inflation adjusted earnings of a company over the past 10 years. Let's use an example to explain.

If we want to calculate the E10 of Wal-Mart (WMT) for Dec. 31, 2010, we need to have the inflation data and the earnings from 2001 through 2010.

We adjusted the earnings of 2001 earnings data with the total inflation from 2001 through 2010 to the equivalent earnings in 2010. If the total inflation from 2001 to 2010 is 40%, and Wal-Mart earned $1 a share in 2001, then the 2001's equivalent earnings in 2010 is $1.4 a share. If Wal-Mart earns $1 again in 2002, and the total inflation from 2002 through 2010 is 35%, then the equivalent 2002 earnings in 2010 is $1.35. So on and so forth, you get the equivalent earnings of past 10 years. Then you add them together and divided the sum by 10 to get E10.

Please note that we use the CPI data of the country/region where the company is headquartered. If the CPI data for that country/region is not available, then we will use the CPI data of the United States as default.

For example, Prothena's adjusted earnings per share data for the three months ended in Jun. 2026 was:

Adj_EPS= Earnings per Share (Diluted) /CPI of Jun. 2026 (Change)*Current CPI (Jun. 2026)
=-0.3564/128.6700*128.6700
=-0.356

Current CPI (Jun. 2026) = 128.6700.

Prothena Quarterly Data

per share eps CPI Adj_EPS
201609 -1.260 100.274 -1.617
201612 -1.410 99.676 -1.820
201703 -0.990 100.374 -1.269
201706 -0.460 100.673 -0.588
201709 -1.370 100.474 -1.754
201712 -1.240 100.075 -1.594
201803 -1.260 100.573 -1.612
201806 -1.500 101.072 -1.910
201809 -0.616 101.371 -0.782
201812 -0.563 100.773 -0.719
201903 -0.523 101.670 -0.662
201906 -0.397 102.168 -0.499
201909 -0.488 102.268 -0.613
201912 -0.540 102.068 -0.681
202003 -0.591 102.367 -0.742
202006 -0.659 101.769 -0.833
202009 -0.766 101.072 -0.975
202012 -0.769 101.072 -0.979
202103 -0.913 102.367 -1.147
202106 0.583 103.364 0.726
202109 2.134 104.859 2.618
202112 -0.711 106.653 -0.858
202203 -0.777 109.245 -0.915
202206 -0.881 112.779 -1.005
202209 -0.974 113.504 -1.104
202212 0.118 115.436 0.131
202303 -0.893 117.609 -0.977
202306 -1.028 119.662 -1.105
202309 0.378 120.749 0.402
202312 -1.257 120.749 -1.340
202403 -1.345 120.990 -1.430
202406 1.215 122.318 1.278
202409 -1.097 121.594 -1.161
202412 -1.077 122.439 -1.132
202503 -1.118 123.405 -1.166
202506 -2.337 124.492 -2.415
202509 -0.679 124.810 -0.700
202512 -0.401 125.770 -0.410
202603 0.605 127.830 0.609
202606 -0.356 128.670 -0.356

Add all the adjusted EPS together and divide 10 will get our e10.

Frequently Asked Questions Learn more about E10 →
What does a E10 of $-3.11 mean?
Prothena (LTS:0Y3M) has a E10 of $-3.11 as of Jun. 2026. E10 represents the company's inflation-adjusted earnings per share over a 10-year period. View historical data on Prothena and its competitors.
Is Prothena's E10 too high?
Prothena's current E10 is $-3.11. Overall, Prothena has a GF Score™ of 73/100 and is considered Possible Value Trap, reflecting its overall financial health beyond just this single metric.
How does Prothena's E10 compare to EVMN and EDIT?
Prothena's E10 of $-3.11 can be compared against companies in the Biotechnology industry. See the competitive comparison table and distribution chart on this page for a detailed peer-by-peer breakdown.
What is a good E10 for a Biotechnology company?
A good E10 depends on the Biotechnology industry context. However, E10 should not be evaluated in isolation — investors should consider it alongside profitability, growth, and financial strength metrics. Use the industry distribution chart on this page to see where any company falls relative to its peers.
What does a high E10 mean?
A high E10 can signal that a stock is expensive relative to its fundamentals. E10 represents the company's inflation-adjusted earnings per share over a 10-year period. View historical data on Prothena and its competitors. Prothena's current E10 is $-3.11. However, context matters — high-growth companies often justify higher valuations. Always evaluate alongside other metrics like GF Score™ and GF Value™.
Is Prothena stock overvalued right now?
Based on GuruFocus' analysis, Prothena (LTS:0Y3M) is currently considered Possible Value Trap. The stock's GF Value™ is $12.82, compared to a current price of $8.48 — trading 33.9% below its estimated fair value. The current E10 is $-3.11. Prothena's overall GF Score™ is 73/100 with 2 warning signs to review. Investors should evaluate multiple metrics — including profitability, growth, and financial strength — before making a decision.
How is E10 calculated?
E10 is calculated from a company's financial statements. For Prothena (LTS:0Y3M), the current E10 is $-3.11 as of Jun. 2026. GuruFocus calculates this using data sourced from SEC filings and annual reports. See the calculation section and 30-year financial data on this page for the full breakdown.

Is Prothena (LTS:0Y3M) Overvalued in 2026?

Based on GuruFocus' analysis, Prothena stock appears to be undervalued. The current stock price of $8.48 is trading 33.9% below its estimated GF Value™ of $12.82. GuruFocus considers Prothena to be Possible Value Trap.

Key valuation signals for LTS:0Y3M:

  • E10: $-3.11
  • GF Value™: $12.82 vs. price of $8.48 (33.9% below fair value)
  • GF Score™: 73/100 with 2 warning signs

No single metric tells the full story. See the LTS:0Y3M stock analysis page for a complete view including 30-year financials, guru trades, and insider activity.


Prothena Business Description

Other Exchanges PRTA:USA0PT:Germany
Address 77 Sir John Rogerson’s Quay, Block C, Grand Canal Docklands, Dublin 2, Dublin, IRL, D02 VK60
Prothena Corp PLC is a late-stage clinical biotechnology company that focuses on protein dysregulation and a pipeline of investigational therapeutics with the potential to change the course of devastating neurodegenerative and rare and peripheral amyloid diseases. Prothena is developing and applying its proprietary CYTOPE technology to target a broad spectrum of intracellular disease pathways in the brain and periphery. The company's pipeline includes both wholly-owned and partnered programs like Prasinezumab, Coramitug (PRX004), BMS-986446 (PRX005), PRX019, TDP-43 CYTOPE, and PRX012-TfR, being developed for the potential treatment of Parkinson's disease, ATTR amyloidosis with cardiomyopathy, Alzheimer's disease, Amyotrophic lateral sclerosis (ALS), and other neurodegenerative diseases.
73GF Score

Get the complete analysis for LTS:0Y3M

E10 is just one metric. See GF Value™, 30-year financials, guru trades, warning signs, and more.

$8.48
Price
$12.82
GF Value