Companies: 10,795·Total market cap: $144.5T
Prothena Corporation plc

Prothena Corporation plc

PRTANASDAQHealthcare● Active
$8.56
$-0.23(-2.62%)
Market Cap$448143709
P/E Ratio—
52W High$11.8
52W Low$4.76
Shares OutstandingFinancialsRevenue

Prothena Corporation plc (PRTA) Shares Outstanding — Overview

Basic and diluted weighted average shares, YoY change, float context, and historical trend from SEC filings and FMP.

PRTA · shares outstanding · updated Jun 8, 2026

Key metrics

Basic Shares Outstanding · Weighted average · fiscal year
53.8M▲ +0.11% YoY Change
FY · as of Dec 31, 2025 · Reported in USD
vs 53.8M in FY 2024
Diluted Shares Outstanding
53.8M
incl. options, RSUs, convertibles
Dilution Spread
+0.00%
Diluted vs Basic
YoY Change
+0.11%
year-over-year
Float (Free Float)
46.2M
publicly tradable shares
88.3% of total
Source: FMP /income-statement · /shares-float · SEC 10-K / 10-QUpdated: 2026-06-08

Shares Outstanding Growth Rate

3-Year CAGRincreasing
+4.3%
2022 → 2025
5-Year CAGRincreasing
+6.2%
2020 → 2025
10-Year CAGRincreasing
+5.9%
2015 → 2025
ⓘ

Negative CAGR typically indicates share buyback or retirement activity. Interpret alongside Splits and Financials tabs. Splits / Financials

Shares outstanding history

↓ Decrease — typically buyback / retirement
↑ Increase — issuance / equity compensation
Latest
* most recent reported · FMP /income-statement · weightedAverageShsOut

Annual shares outstanding by year

FY 2025Latest
Diluted Shares: 53.8M
53.8M
+0.11%
FY 2024
Diluted Shares: 53.8M
53.8M
+1.04%
FY 2023
Diluted Shares: 53.2M
53.2M
+12.34%
FY 2022
Diluted Shares: 47.4M
47.4M
+7.10%
FY 2021
Diluted Shares: 48.5M
44.2M
+10.81%
FMP /income-statement · weightedAverageShsOut · weightedAverageShsOutDilUnit: Billions (B)

Healthcare sector shares outstanding comparison

Shares Outstanding for similar companies or competitors in the Healthcare sector.

#SymbolCompanyShares (Basic)vs PRTA
#1
Merck & Co., Inc.MRK
Merck & Co., Inc.
2.502B+>999%
#2
Johnson & JohnsonJNJ
Johnson & Johnson
2.429B+>999%
#3
AbbVie Inc.ABBV
AbbVie Inc.
1.780B+>999%
#4
AstraZeneca PLCAZN
AstraZeneca PLC
1.550B+>999%
#5
UnitedHealth Group IncorporatedUNH
UnitedHealth Group Incorporated
910.0M+>999%
#6
Eli Lilly and CompanyLLY
Eli Lilly and Company
898.0M+>999%
#7
Prothena Corporation plcPRTA
Prothena Corporation plcYOU
53.8M—

/company-screener · per-peer /income-statement · cache 86400s

Understanding Shares Outstanding

What Are Shares Outstanding? (Basic)

Prothena Corporation plc (PRTA) shares outstanding is the total number of issued shares held by shareholders — the basis for Basic EPS and market capitalization. As of December 31, 2025, Prothena Corporation plc reports 53.8M basic shares outstanding (weighted average).

Basic vs. Diluted Shares Outstanding

Prothena Corporation plc's basic shares outstanding (53.8M) represents currently issued shares. Diluted shares outstanding (53.8M) also includes potential shares from stock options, RSUs, and convertibles. Dilution spread: +0.00%.

Shares Outstanding vs. Float (Free Float)

Prothena Corporation plc's float is 46.2M (88.3% of total shares outstanding) — shares freely available for public trading, excluding insider-held and restricted shares.

Float46.2M(88.3%)
Outstanding52.4M

ⓘ Float data from /shares-float reflects the most recent SEC filing period-end. The weighted average shares (from /income-statement) may differ — this is a normal reporting window difference, not a data error.

FMP /income-statement · /shares-float · SEC EDGAR · USD

About shares outstanding & methodology

Prothena Corporation plc (PRTA) shares outstanding history from 2010 to 2025. Shares outstanding can be defined as the total number of shares held by all shareholders — including institutional investors, retail investors, and company insiders — assuming conversion of all convertible debt, securities, warrants, and options. This metric excludes the company's treasury shares.

Prothena Corporation plc shares outstanding for the fiscal year ending December 31, 2025 were 53.8M, a 0.11% increase year-over-year. Prothena Corporation plc FY 2025 shares outstanding were 53.8M, a +0.11% increase from FY 2024.

Prothena Corporation plc is a leading company operating in the Healthcare sector. The company's share count trajectory — with a 10-year CAGR of +5.9% — is a key signal for investors evaluating capital return policy, EPS accretion, and long-term shareholder value creation.

Figures tie to SEC 10-K/10-Q income statement disclosures and FMP /income-statement · /shares-float where noted.
Market capSplitsEarningsFinancials (Income)Cash on handFree cash flowNet incomePrice history

Frequently asked questions

PRTA shares outstanding · 4 questions

As of December 31, 2025, Prothena Corporation plc (PRTA) has approximately 53.8M basic shares outstanding and 53.8M diluted shares outstanding. This represents a +0.11% year-over-year increase from FY 2024 (53.8M). The increase may reflect equity compensation issuances or secondary offerings.

PRTA shares outstandinghow many shares does PRTA havePRTA basic shares 2025PRTA diluted shares

▸ Data: FMP /income-statement · /shares-float · SEC EDGAR · weighted average basis · Prothena Corporation plc SEC 10-K & 10-Q filings · US GAAP · Last updated: 2026-06-08