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Investment Highlights Market Valuation Price Chart Business Description Interactive Breakdown Latest Trefis Analyses Better Bets vs. PRTA Recent Active Movers More From Trefis Peer Financials Peer Growth & Margins Peer Valuation Peer Returns Peer Analyses FDIC Bank Data Financials Segment Financials Price Behavior Short Interest Earnings Returns History SEC Filings Insider Activity Industry Resource Links External Quote Links

Prothena (PRTA)

Market Price (9/18/2025): $8.06 | Market Cap: $433.8 Mil
Sector: Health Care | Industry: Biotechnology

Prothena (PRTA)

Market Price (9/18/2025): $8.06
Market Cap: $433.8 Mil
Sector: Health Care
Industry: Biotechnology

Investment Highlights

0 Cash is significant % of market cap
Net D/ENet Debt/Equity. Debt net of cash. Negative indicates net cash. Equity is taken as the Market Capitalization is -83%		 Weak multi-year price returns
2Y Excs Rtn is -133%, 3Y Excs Rtn is -133%		 Not profitable at operating income level
Op Inc LTMOperating Income, Last Twelve Months is -249 Mil, Op Mgn LTMOperating Margin = Operating Income / Revenue Reflects profitability before taxes and before impact of capital structure (interest payments). is -2408%
1   Weak revenue growth
Rev Chg LTMRevenue Change % Last Twelve Months (LTM) is -95%, Rev Chg QQuarterly Revenue Change % is -97%
2   Not cash flow generative
CFO/Rev LTMCash Flow from Operations / Revenue (Sales), Last Twelve Months (LTM) is -1863%, FCF/Rev LTMFree Cash Flow / Revenue (Sales), Last Twelve Months (LTM) is -1865%
3   Valuation getting more expensive
P/S 6M Chg %Price/Sales change over 6 months. Declining P/S indicates valuation has become less expensive. is 473%
4   Yield minus risk free rate is negative
ERPEquity Risk Premium (ERP) = Total Yield - Risk Free Rate, Reflects the premium above risk free assets offered by the investment. is -74%
0 Cash is significant % of market cap
Net D/ENet Debt/Equity. Debt net of cash. Negative indicates net cash. Equity is taken as the Market Capitalization is -83%
1 Weak multi-year price returns
2Y Excs Rtn is -133%, 3Y Excs Rtn is -133%
2 Not profitable at operating income level
Op Inc LTMOperating Income, Last Twelve Months is -249 Mil, Op Mgn LTMOperating Margin = Operating Income / Revenue Reflects profitability before taxes and before impact of capital structure (interest payments). is -2408%
3 Weak revenue growth
Rev Chg LTMRevenue Change % Last Twelve Months (LTM) is -95%, Rev Chg QQuarterly Revenue Change % is -97%
4 Not cash flow generative
CFO/Rev LTMCash Flow from Operations / Revenue (Sales), Last Twelve Months (LTM) is -1863%, FCF/Rev LTMFree Cash Flow / Revenue (Sales), Last Twelve Months (LTM) is -1865%
5 Valuation getting more expensive
P/S 6M Chg %Price/Sales change over 6 months. Declining P/S indicates valuation has become less expensive. is 473%
6 Yield minus risk free rate is negative
ERPEquity Risk Premium (ERP) = Total Yield - Risk Free Rate, Reflects the premium above risk free assets offered by the investment. is -74%

Market Valuation

 9/18/252024202320222021
Share Price CYE$8.06$13.85$36.34$60.25$49.40
Market Cap CYE ($ Mil)433.8745.41,950.42,950.92,304.3
Total Debt ($ Mil)9.810.811.86.512.3
Total Cash ($ Mil)371.4471.4618.8710.4579.1
Enterprise Value ($ Mil)72.2756.21,962.22,957.42,316.6
Valuation Ratios     
P/S TTM42.05.521.252.910.9
P/EBIT TTM-1.7-4.8-10.1-21.730.4
P/E TTM-1.4-6.1-13.2-24.432.6
Sector Ratios     
P/S TTM (Sector)3.83.64.14.57.3
P/EBIT TTM (Sector)-1.6-1.3-1.4-1.3-2.9
P/E TTM (Sector)-1.8-1.5-1.5-1.3-2.9
 9/18/2520242023
Share Price CYE$8.06$13.85$36.34
Market Cap CYE ($ Mil)433.8745.41,950.4
Total Debt ($ Mil)9.810.811.8
Total Cash ($ Mil)371.4471.4618.8
Enterprise Value ($ Mil)72.2756.21,962.2
Valuation Ratios   
P/S TTM42.05.521.2
P/EBIT TTM-1.7-4.8-10.1
P/E TTM-1.4-6.1-13.2
Sector Ratios   
P/S TTM (Sector)3.83.64.1
P/EBIT TTM (Sector)-1.6-1.3-1.4
P/E TTM (Sector)-1.8-1.5-1.5

Market Cap Chart

Business Description

Prothena Corporation plc, a late-stage clinical company, focuses on discovery and development of novel therapies for life-threatening diseases in the United States. The company is involved in developing Birtamimab, an investigational humanized antibody that is in Phase III clinical trial for the treatment of AL amyloidosis; Prasinezumab, a humanized monoclonal antibody, which is in Phase IIb clinical trial for the treatment of Parkinson's disease; PRX004 that completed Phase I clinical trial for the treatment of Transthyretin amyloidosis; and PRX005, which is in Phase I clinical trial for the treatment of Alzheimer's disease. Its discovery and preclinical programs include PRX012 for the treatment of Alzheimer's disease; and dual Aß-Tau vaccine for the treatment and prevention of Alzheimer's disease. Show more

Price Returns Compared

Expand for Detailed View

 202020212022202320242025Total [1]
Returns
PRTA Return-24%311%22%-40%-62%-42%-48%
Peers Return11%18%23%15%2%8%103%
S&P 500 Return16%27%-19%24%23%12%104%

[1] Cumulative total returns since the beginning of 2020
[2] Peers: VRTX, ABBV, AMGN, GILD, REGN. See PRTA Returns vs. Peers.
[3] 2025 data is for the year up to 9/17/2025 (YTD)

Better Bets than Prothena (PRTA)

 PRTABetter Performance than PRTA
MetricValueIndustry (Biotechnology)
Rev Chg LTM-95.2%ABBV (6.1%), AMGN (12.9%), GILD (3.8%), VRTX (10.5%), REGN (5.4%)
Rev Chg 3Y Avg40.7%ALNY (40.8%), BBIO (1225.0%), RYTM (137.5%), AXSM (699.5%), CYTK (824.6%)
Op Mgn LTM-2407.9%ABBV (23.5%), AMGN (23.5%), GILD (37.4%), VRTX (-1.7%), REGN (27.0%)
CFO/Rev LTM-1863.1%ABBV (33.1%), AMGN (34.4%), GILD (34.2%), VRTX (33.7%), REGN (33.4%)
FCF/Rev LTM-1864.8%ABBV (31.3%), AMGN (30.4%), GILD (32.5%), VRTX (30.6%), REGN (25.0%)
Total Yield-69.8%ABBV (3.9%), AMGN (7.8%), GILD (7.3%), VRTX (3.7%), REGN (7.5%)
 PRTABetter Performance than PRTA
MetricValueAll Other Sectors
Rev Chg LTM-95.2%NVDA (71.6%), MSFT (14.9%), AAPL (6.0%), GOOGL (13.1%), AMZN (10.9%)
Rev Chg 3Y Avg40.7%NVDA (92.0%), RCL (65.4%), APO (129.8%), NU (70.1%), RDDT (42.6%)
Op Mgn LTM-2407.9%NVDA (58.1%), MSFT (45.6%), AAPL (31.9%), GOOGL (32.7%), AMZN (11.4%)
CFO/Rev LTM-1863.1%NVDA (46.6%), MSFT (48.3%), AAPL (26.6%), GOOGL (36.0%), AMZN (18.1%)
FCF/Rev LTM-1864.8%NVDA (43.6%), MSFT (25.4%), AAPL (23.5%), GOOGL (18.0%), AMZN (2.0%)
Total Yield-69.8%NVDA (2.1%), MSFT (3.3%), AAPL (3.2%), GOOGL (4.1%), AMZN (2.9%)

Latest Trefis Analyses

TitleTopicDate
0DASHBOARDS  
1Day 5 of Gains Streak for Prothena Stock with 19% Return (vs. 13% YTD) [1/27/2025]Notification 
2Day 0 of Loss Streak for Prothena Stock with 0% Return (vs. 13% YTD) [1/26/2025]Notification 
3Day 5 of Gains Streak for Prothena Stock with 19% Return (vs. 13% YTD) [1/25/2025]Notification 
4Day 0 of Loss Streak for Prothena Corp Stock with 0% Return (vs. -55% YTD) [12/2/2024]Notification 
5Day 0 of Loss Streak for Prothena Corp Stock with 0% Return (vs. -56% YTD) [11/30/2024]Notification 
6Prothena vs. S&P500 CorrelationCorrelation 
7Prothena Price VolatilityVolatility 
8Day 5 of Loss Streak for Prothena Corporation Stock with -26% Return (vs. -31% YTD) [2/6/2024]Notification 
9Day 1 of Gains Streak for Prothena Corporation Stock with 0.04% Return (vs. -44% YTD) [10/27/2023]Notification 
10Day 8 of Loss Streak for Prothena Corporation Stock with -45% Return (vs. -52% YTD) [10/26/2023]Notification 
11ARTICLES  
12Will Prothena Stock Rebound After A 13% Drop Last Week? June 23rd, 2021
13What’s Next For Prothena Stock After A 9% Rise This Week? April 16th, 2021
Title
0DASHBOARDS
1Will Prothena Stock Rebound After A 13% Drop Last Week?
2What’s Next For Prothena Stock After A 9% Rise This Week?
3ARTICLES
4Day 5 of Gains Streak for Prothena Stock with 19% Return (vs. 13% YTD) [1/27/2025]
5Day 0 of Loss Streak for Prothena Stock with 0% Return (vs. 13% YTD) [1/26/2025]
6Day 5 of Gains Streak for Prothena Stock with 19% Return (vs. 13% YTD) [1/25/2025]
7Day 0 of Loss Streak for Prothena Corp Stock with 0% Return (vs. -55% YTD) [12/2/2024]
8Day 0 of Loss Streak for Prothena Corp Stock with 0% Return (vs. -56% YTD) [11/30/2024]
9Prothena vs. S&P500 Correlation
10Prothena Price Volatility
11Day 5 of Loss Streak for Prothena Corporation Stock with -26% Return (vs. -31% YTD) [2/6/2024]
12Day 1 of Gains Streak for Prothena Corporation Stock with 0.04% Return (vs. -44% YTD) [10/27/2023]
13Day 8 of Loss Streak for Prothena Corporation Stock with -45% Return (vs. -52% YTD) [10/26/2023]

Recent Active Movers

1 Week Top Gainers

#TickerCompany1W RtnYTD Rtn
1ECDAECD Automotive Design3347.2%307.9%
2BDSXBiodesix1090.6%-79.7%
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4ATHAAthira Pharma892.1%544.3%
5SDOTSadot690.6%-79.9%
6ATCHAtlasClear684.9%-83.1%
7HSDTHelius Medical Technologies232.1%-95.5%
8CHEKCheck-Cap222.2%134.4%
9APLMApollomics197.8%89.1%
10SPRCSciSparc147.0%1141.7%

1 Week Top Losers

#TickerCompany1W RtnYTD Rtn
1CURXCuranex Pharmaceuticals-80.5%148.4%
2ATYRaTyr Pharma-80.4%-71.7%
3NAKAKindly MD-70.2% 
4BNGOBionano Genomics-64.0%-89.8%
5XAGELongevity Health-57.6%-86.1%
6FAASDigiAsia-55.4%-88.0%
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8VCIGVCI Global-51.0%-98.9%
9REXREX American Resources-50.7%44.3%
10RBNERobin Energy-42.6% 

1 Month Top Gainers

#TickerCompany1M RtnYTD Rtn
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10BCTXBriaCell Therapeutics1032.4%-89.8%

1 Month Top Losers

#TickerCompany1M RtnYTD Rtn
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2STFSStar Fashion Culture-92.3%-97.9%
3ELPWElong Power-91.1%-76.9%
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5EPIXESSA Pharma-89.4%-8.9%
6NAKAKindly MD-88.1% 
7BINIBollinger Innovations-87.6%-100.0%
8JEM707 Cayman-87.4%-98.2%
9YAASYouxin Technology-83.3%-98.4%
10NEONNeonode-82.5%-51.0%

Recent Active Movers

1 Week Top Gainers

#TickerCompany1W RtnYTD Rtn
1ECDAECD Automotive Design3347.2%307.9%
2BDSXBiodesix1090.6%-79.7%
3CLSDClearside Biomedical987.7%-74.7%
4ATHAAthira Pharma892.1%544.3%
5SDOTSadot690.6%-79.9%
6ATCHAtlasClear684.9%-83.1%
7HSDTHelius Medical Technologies232.1%-95.5%
8CHEKCheck-Cap222.2%134.4%
9APLMApollomics197.8%89.1%
10SPRCSciSparc147.0%1141.7%

1 Week Top Losers

#TickerCompany1W RtnYTD Rtn
1CURXCuranex Pharmaceuticals-80.5%148.4%
2ATYRaTyr Pharma-80.4%-71.7%
3NAKAKindly MD-70.2% 
4BNGOBionano Genomics-64.0%-89.8%
5XAGELongevity Health-57.6%-86.1%
6FAASDigiAsia-55.4%-88.0%
7ASSTStrive-54.5%650.3%
8VCIGVCI Global-51.0%-98.9%
9REXREX American Resources-50.7%44.3%
10RBNERobin Energy-42.6% 

More From Trefis

Research & Analysis

Invest in Strategies

Wealth Management

Peer Comparisons for Prothena

Financials

PRTAVRTXABBVAMGNGILDREGNMedian
NameProthena Vertex P.AbbVie Amgen Gilead S.Regenero. 
Mkt Price8.06387.15220.81274.71112.26585.50247.76
Mkt Cap0.499.4390.4147.8139.861.5119.6
Rev LTM1011,41958,32834,91728,86214,21421,538
Op Inc LTM-249-19913,6958,19210,7973,8416,016
FCF LTM-1933,50018,23910,6059,3693,5566,463
FCF 3Y Avg-1411,98420,2738,5908,3973,2485,823
CFO LTM-1933,84619,28312,0139,8684,7447,306
CFO 3Y Avg-1402,32421,1549,7538,9494,5186,733

Growth & Margins

PRTAVRTXABBVAMGNGILDREGNMedian
NameProthena Vertex P.AbbVie Amgen Gilead S.Regenero. 
Rev Chg LTM-95.2%10.5%6.1%12.9%3.8%5.4%5.7%
Rev Chg 3Y Avg40.7%11.0%0.6%10.0%1.6%0.3%5.8%
Rev Chg Q-96.7%12.1%6.6%9.4%1.8%3.6%5.1%
QoQ Delta Rev Chg LTM-92.5%2.9%1.7%2.3%0.4%0.9%1.3%
Op Mgn LTM-2,407.9%-1.7%23.5%23.5%37.4%27.0%23.5%
Op Mgn 3Y Avg-916.8%26.5%27.2%26.4%39.2%30.1%26.8%
QoQ Delta Op Mgn LTM-2,307.4%2.0%1.0%1.6%-0.0%-0.2%0.5%
CFO/Rev LTM-1,863.1%33.7%33.1%34.4%34.2%33.4%33.5%
CFO/Rev 3Y Avg-710.5%22.5%37.5%32.0%31.9%33.6%31.9%
FCF/Rev LTM-1,864.8%30.6%31.3%30.4%32.5%25.0%30.5%
FCF/Rev 3Y Avg-712.1%19.2%36.0%28.2%30.0%24.1%26.1%

Valuation

PRTAVRTXABBVAMGNGILDREGNMedian
NameProthena Vertex P.AbbVie Amgen Gilead S.Regenero. 
Mkt Cap0.499.4390.4147.8139.861.5119.6
P/S42.08.76.74.24.84.35.8
P/EBIT-1.722.666.314.317.012.515.7
P/E-1.427.3103.722.322.113.822.2
P/CFO-2.325.820.212.314.213.013.6
Total Yield-69.8%3.7%3.9%7.8%7.3%7.5%5.6%
Dividend Yield0.0%0.0%2.9%3.4%2.8%0.3%1.6%
FCF Yield 3Y Avg-23.9%2.1%7.3%6.2%8.0%4.4%5.3%
D/E0.00.00.20.40.20.00.1
Net D/E-0.8-0.00.20.30.1-0.10.0

Returns

PRTAVRTXABBVAMGNGILDREGNMedian
NameProthena Vertex P.AbbVie Amgen Gilead S.Regenero. 
1M Rtn-5.5%-0.7%6.9%-6.1%-4.2%2.0%-2.4%
3M Rtn40.2%-13.7%20.1%-4.4%4.7%14.2%9.4%
6M Rtn-37.4%-24.5%5.9%-11.5%5.9%-12.7%-12.1%
12M Rtn-63.3%-19.6%18.2%-14.7%39.2%-48.7%-17.1%
3Y Rtn-72.6%33.6%71.6%30.8%90.5%-17.2%32.2%
1M Excs Rtn-7.9%-3.0%4.5%-8.5%-6.5%-0.3%-4.8%
3M Excs Rtn31.1%-22.7%9.8%-14.8%-5.7%4.9%-0.4%
6M Excs Rtn-54.7%-42.0%-12.4%-29.9%-14.3%-29.2%-29.6%
12M Excs Rtn-80.9%-37.6%0.4%-31.9%22.3%-66.3%-34.7%
3Y Excs Rtn-133.4%-28.7%13.2%-33.4%25.2%-77.8%-31.0%

Financials

$ Mil | FY: 12/312025Q22025Q12024Q42024Q32024Q22024Q12023Q42023Q32023Q22023Q12022Q42022Q3
Period End6/30/20253/31/202512/31/20249/30/20246/30/20243/31/202412/31/20239/30/20236/30/20233/31/202312/31/20229/30/2022
Filing Date8/4/20255/8/20252/27/202511/12/20248/8/20245/8/20242/22/202411/2/20238/3/20235/4/20232/28/202311/3/2022
Key Financials Quarterly            
Total Revenue4321132008542502
Ebitda-52-65-65-6659-81-7811-66-56-0-46
Operating Income-52-66-65-6758-82-7910-67-56-0-50
Net Income-126-60-58-5967-72-6722-55-476-46
EPS-2.34-1.12-1.08-1.101.24-1.34-1.260.41-1.03-0.890.13-0.97
Key Financials TTM            
Total Revenue TTM1013813513321789911415855545
Ebitda TTM-248-138-154-167-90-215-190-112-168-145-127-160
Operating Income TTM-249-139-155-168-91-216-191-113-173-150-132-165
Net Income TTM-303-110-122-132-51-172-147-73-141-128-117-156
Growth Rates Quarterly            
Total Revenue Growth-96.7%5556.0%571.8%-98.9%3184.7%-97.7%-99.4%5494.3%206.3%88.1%4159.6%-98.9%
EBITDA Growth-188.4%19.6%17.3%-729.1%188.4%-44.9%-108565.3%123.1%-54.1%-48.6%99.8%-141.2%
Operating Income Growth-189.1%19.6%17.3%-745.3%187.8%-44.7%-108948.6%120.5%-53.9%-48.4%99.8%-146.1%
Net Income Growth-288.0%16.7%14.1%-369.3%222.5%-54.1%-1162.8%147.9%-32.4%-29.1%119.1%-141.9%
Margins Quarterly            
EBITDA Margin-1171.5%-2311.1%-3046.4%-6833.7%44.4%-162626.0%-24759.2%12.4%-1649.2%-2587.6%-0.1%-3011.5%
Operating Income Margin-1176.6%-2319.0%-3056.9%-6857.0%44.2%-163056.0%-24846.5%12.1%-1654.7%-2596.8%-0.1%-3317.9%
Net Income Margin-2845.4%-2128.5%-2729.9%-6082.6%50.7%-144478.0%-21353.2%25.8%-1358.4%-2160.6%12.7%-3016.7%
Cash & Debt            
Total Cash371418471519564547619671659686710496
Total Debt10101111121212113568
Net Debt / (Cash)-362-408-461-508-552-534-607-660-656-681-704-488
Cash Flows Quarterly            
FCF from Operations-46-53-48-4516-73-5110-45-47-5-31
Cash Flows TTM            
FCF from Operations TTM-193-130-150-153-99-159-134-88-129-119-109-126
Returns to Shareholders Quarterly            
Dividends000000000000
Share Repurchases000000-0-0-00-0-0
Return on Invested Capital (ROIC) Quarterly            
ROIC-16.6%-21.6%-22.4%-24.5%23.0%-31.0%-32.1%4.7%-28.7%-26.3%-0.0%-25.2%
Return on Invested Capital (ROIC) TTM            
ROIC TTM-19.9%-11.1%-13.0%-14.8%-7.5%-19.7%-18.7%-11.0%-18.4%-17.3%-16.3%-21.0%

Price Behavior

PRTA Betas & Captures as of 8/31/2025

 1M2M3M6M1Y3Y
Beta1.431.702.010.400.721.22
Up Beta0.581.323.19-0.210.001.06
Down Beta1.051.451.111.081.451.44
Up Capture291%316%361%-6%20%64%
Bmk +ve Days10223571142415
Stock +ve Days10213560124359
Down Capture29%65%-17%112%126%107%
Bmk -ve Days11192754106334
Stock -ve Days10192663122386

[1] Upside and downside betas calculated using positive and negative benchmark daily returns respectively

Short Interest

Short Interest: As Of Date8292025
Short Interest: Shares Quantity4,055,435
Short Interest: % Change Since 8152025-3.1%
Average Daily Volume1,041,258
Days-to-Cover Short Interest3.89
Basic Shares Quantity53,827,000
Short % of Basic Shares7.5%

Returns Analyses

Earnings Returns History

Expand for More

 Forward Returns
Earnings Date1D Returns5D Returns21D Returns
8/4/20251.3%10.5%20.9%
5/8/20254.6%-5.4%-26.1%
2/20/20252.0%-0.8%-15.0%
11/12/2024-0.7%-19.1%-20.4%
8/8/20244.4%6.0%3.7%
5/8/2024-4.5%-2.8%-8.3%
2/15/2024-1.8%-4.6%-12.0%
11/2/20237.4%-6.3%0.9%
...
SUMMARY STATS   
# Positive10910
# Negative141514
Median Positive4.4%4.7%14.2%
Median Negative-4.3%-4.6%-16.0%
Max Positive12.0%51.0%93.8%
Max Negative-8.3%-19.1%-26.1%

SEC Filings

Expand for More

Report DateFiling DateFiling
6302025804202510-Q 6/30/2025
3312025508202510-Q 3/31/2025
12312024227202510-K 12/31/2024
93020241112202410-Q 9/30/2024
6302024808202410-Q 6/30/2024
3312024508202410-Q 3/31/2024
12312023222202410-K 12/31/2023
93020231102202310-Q 9/30/2023
6302023803202310-Q 6/30/2023
3312023504202310-Q 3/31/2023
12312022228202310-K 12/31/2022
93020221103202210-Q 9/30/2022
6302022808202210-Q 6/30/2022
3312022505202210-Q 3/31/2022
12312021225202210-K 12/31/2021
93020211104202110-Q 9/30/2021

Insider Activity

Expand for More

 OwnerTitleFiling DateActionPriceSharesTransacted
Value		Value of
Held Shares		Form
0EcoR1 Capital, LLC5062025Sell8.363,317,93827,744,92969,123,978Form

Industry Resources

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