Prothena (PRTA) - Shares outstanding

Number of shares outstanding as of October 2026 : 52,145,000

According to Prothena's latest financial reports and stock price the company's current number of shares outstanding is 52,145,000. At the end of 2026 the company had 52,145,000 shares outstanding. The number of outstanding shares is usually impacted by stock plits and shares buy back.

Shares outstanding history for Prothena from 2012 to 2026

Shares Outstanding at the end of each year

Year	Shares Outstanding	Change
2026	52.14 M	-3.13%
2025	53.83 M	0.03%
2024	53.81 M	0.27%
2023	53.66 M	9.62%
2022	48.96 M	5.02%
2021	46.61 M	16.78%
2020	39.92 M	0.06%
2019	39.89 M	0.08%
2018	39.86 M	3.66%
2017	38.45 M	11.13%
2016	34.6 M	9.47%
2015	31.61 M	15.44%
2014	27.38 M	28%
2013	21.39 M	43.72%
2012	14.88 M

Shares Outstanding for similar companies or competitors

Company	Shares Outstanding	differencediff.	Country
Amarin Corporation AMRN	20,822,200	-60.07%	🇮🇪 Ireland
Alnylam Pharmaceuticals ALNY	133,606,000	156.22%	🇺🇸 USA
Alkermes ALKS	167,026,000	220.31%	🇮🇪 Ireland

What is the market capitalization of a company?

The market capitalization sometimes referred as Marketcap, is the value of a publicly listed company.
In most cases it can be easily calculated by multiplying the share price with the amount of outstanding shares.

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Number of shares outstanding for Prothena (PRTA)

Number of shares outstanding as of October 2026 : 52,145,000