PRTA Prothena Corp Public (PRTA) Insider Trading, Ownership & Congress Trades
Pharma & Biotech · Pharmaceutical preparations · CIK 0001559053
Form 144 · 2
House members buying, 1 year
0
STOCK Act, US House only, disclosed up to 45 days after the trade
Funds added, last quarter
0
13F, latest reported quarter
Conversions, 180 days
6
Codes C/M, not in net · no price filed
What the filings say about PRTA
Insiders, 180 days
+$11.9M net bought
1 buyer · 2 sellers · 0% of sales under a 10b5-1 plan
Planned sales (Form 144), 90 days
$136.0K
2 notices
Prothena Corp Public insider trades (Form 4)
Form 4 buys and sells (codes P and S). Grants, option exercises
and conversions excluded.
Over the last 180 days, PROTHENA CORP PUBLIC LTD CO insiders bought a net $11.9M of stock across 288 Form 4 purchases and sales, with 1 insider buying. Source: SEC Form 4 filings, as of 2026-10-28.
Insider
Filed
Shares
Value
Since filing
Context
- 24 earlier Form 4 trades (code P or S) here by this insider (24 buys), the last on Oct 22, 2026.
- +1.7% median (-2.5% mean) 90-day return after 9 previous buys.
- The trade is 4.2% of the 1,187,000 shares held after it.
- No other insider bought within 30 days.
Insider activity: Insider SCULLY WILLIAM P bought about $403.5K of PRTA on Oct 23, 2026.Context
- 23 earlier Form 4 trades (code P or S) here by this insider (23 buys), the last on Oct 14, 2026.
- +1.7% median (-2.5% mean) 90-day return after 9 previous buys.
- The trade is 8.8% of the 1,137,000 shares held after it.
- No other insider bought within 30 days.
Insider activity: Insider SCULLY WILLIAM P bought about $818.5K of PRTA on Oct 22, 2026.Context
- 22 earlier Form 4 trades (code P or S) here by this insider (22 buys), the last on Oct 13, 2026.
- +1.7% median (-2.5% mean) 90-day return after 9 previous buys.
- The trade is 1.0% of the 1,037,000 shares held after it.
- No other insider bought within 30 days.
Insider activity: Insider SCULLY WILLIAM P bought about $84.6K of PRTA on Oct 14, 2026.Context
- 21 earlier Form 4 trades (code P or S) here by this insider (21 buys), the last on Oct 8, 2026.
- +1.7% median (-2.5% mean) 90-day return after 9 previous buys.
- The trade is 9.7% of the 1,027,000 shares held after it.
- No other insider bought within 30 days.
Insider activity: Insider SCULLY WILLIAM P bought about $835.5K of PRTA on Oct 13, 2026.Context
- 20 earlier Form 4 trades (code P or S) here by this insider (20 buys), the last on Oct 7, 2026.
- +1.7% median (-2.5% mean) 90-day return after 9 previous buys.
- The trade is 17.0% of the 529,000 shares held after it.
- No other insider bought within 30 days.
Insider activity: Insider SCULLY WILLIAM P bought about $770.9K of PRTA on Oct 8, 2026.288 transactions on record
Since filing: total return from the first close after the filing to the latest close, dividend-adjusted. Not a forecast.
Context lines are counts over the filings above and returns from our own price history, never a price level. Not investment advice.
Seven facts, ranked against the sector ·
Rank is not a forecast
Insiders
net +$11.9M over 180 days
+$8.8M over 90 days · +$12.1M of it by a 10%+ holder
more than 96% of Pharma & Biotech
Congress
no House purchase disclosed in the last 12 months
Funds
under five funds report holding it
Revenue
-92.8% year over year
below 90% of Pharma & Biotech
Margin
-2520.6% net margin
below 93% of Pharma & Biotech
Buybacks
no share repurchases reported
Short interest
23.5% of the float short (float per yahoo 2026-10-26) · 13.8 days to cover · settled 2026-09-30
more than 86% of Pharma & Biotech
What changed in the last 30 days
Oct 26Insider SCULLY WILLIAM P bought $7.1M (9 trades, Sep 28 to Oct 23)
Watch PRTA
A free account keeps a watchlist and can send one email a day when insiders, funds or Congress file on the names in it. No password and no card.
The year, with the filings on it
Total return over 12 months. Each marker is a filing; hover or tap one for the detail.
-13.8%12M
Insider buyInsider sellForm 144 (planned sale)
Indexed to 100, dividend-adjusted, not a price chart.
When a name files heavily, the largest trades are drawn first.
Who owns PRTA: institutional holders (13F)
13F holdings, latest reported quarter
SEC 13F
No reported 13F holders
No fund above the reporting threshold listed this stock last quarter. That is a fact, not missing data.
Congress trades in PRTA
No Congress trades reported
No House member has disclosed a trade in this stock. See what Congress is buying.
Activist and 5% holders (13D/13G)
No 5%+ ownership filings
Nobody has filed for crossing 5%. That is a fact, not missing data.
PRTA planned insider sales (Form 144)
Notice of intent to sell, filed before any sale
MICHAEL JOHN ISAACS
Filed 2026-07-29
$71.1K
ANNE KINGSTON
Filed 2026-07-29
$64.9K
Executive pay vs shareholder return · Gene G. Kinney
CEO pay, headline and as actually paid, against the company's
return and its chosen peers' (DEF 14A).
FY
CEO total
Actually paid
Other execs, avg
TSR
Peer TSR
2025
$5.9M
$2.9M
$2.6M
-20%
+20%
2024
$7.2M
-$1.7M
$2.5M
+15%
-9%
2023
$7.0M
-$3.2M
$2.6M
+203%
-8%
2022
$6.7M
$7.4M
$2.7M
+402%
-11%
2021
$4.9M
$41.1M
$2.9M
+311%
-1%
Tagged by the company under SEC Item 402(v). Returns are
cumulative from the start of the disclosure period. Green where the company beat its own peer group.
Live price
Daily candles from TradingView, under their licence. No filings marked.
Why this name is on the desk
Insiders are net buyers of their own stock.
The record shows a net $11.9M bought by insiders over 180 days, $136.0K in planned Form 144 sales. Each figure is a federal filing, dated the day it went public.
PRTA financials
Revenue growth
-92.8%
XBRL, annual
Net margin
-2520.6%
Ratios from the company's XBRL filings, latest filings
Revenue, TTM
$54.5M
four quarters, 2025-07-01 to 2026-06-30
Revenue, TTM PRTA
| FY Dec 2025 | $9.7M |
| FY Dec 2024 | $135.2M |
| FY Dec 2023 | $91.4M |
| FY Dec 2022 | $53.9M |
| FY Dec 2021 | $200.6M |
| Jun 2026 | $1.0M |
| Mar 2026 | $51.1M |
| Dec 2025 | $21.0K |
| Sep 2025 | $2.4M |
| Jun 2025 | $4.4M |
| Mar 2025 | $2.8M |
| Dec 2024 | $2.1M |
| Sep 2024 | $970.0K |
At each fiscal year end
Single quarter
Net margin, TTM
-80.7%
net income over revenue, 2025-07-01 to 2026-06-30
Net margin, TTM PRTA
| FY Dec 2025 | -2,521% |
| FY Dec 2024 | -90.5% |
| FY Dec 2023 | -160.9% |
| FY Dec 2022 | -217.0% |
| FY Dec 2021 | +33.4% |
| Jun 2026 | -1,840% |
| Mar 2026 | +64.1% |
| Dec 2025 | n/a |
| Sep 2025 | -1,513% |
| Jun 2025 | -2,845% |
| Mar 2025 | -2,129% |
| Dec 2024 | -2,730% |
| Sep 2024 | -6,083% |
At each fiscal year end
Single quarter
Free cash flow, TTM
-$60.7M
operating cash flow minus capex, 2025-07-01 to 2026-06-30
Free cash flow, TTM PRTA
| FY Dec 2025 | -$163.7M |
| FY Dec 2024 | -$150.3M |
| FY Dec 2023 | -$136.7M |
| FY Dec 2022 | -$109.3M |
| FY Dec 2021 | $92.0M |
| Jun 2026 | -$25.7M |
| Mar 2026 | $28.9M |
| Dec 2025 | -$23.3M |
| Sep 2025 | -$40.6M |
| Jun 2025 | -$46.4M |
| Mar 2025 | -$53.4M |
| Dec 2024 | -$47.8M |
| Sep 2024 | -$45.2M |
At each fiscal year end
Single quarter
Debt to equity
n/a
no debt line filed
Debt to equity PRTA
| FY Dec 2025 | n/a |
| FY Dec 2024 | n/a |
| FY Dec 2023 | n/a |
| FY Dec 2022 | n/a |
| FY Dec 2021 | n/a |
| Jun 2026 | n/a |
| Mar 2026 | n/a |
| Dec 2025 | n/a |
| Sep 2025 | n/a |
| Jun 2025 | n/a |
| Mar 2025 | n/a |
| Dec 2024 | n/a |
| Sep 2024 | n/a |
At each fiscal year end
Trailing four quarters at each quarter end
Cash flow to debt
n/a
no debt line filed
Cash flow to debt PRTA
| FY Dec 2025 | n/a |
| FY Dec 2024 | n/a |
| FY Dec 2023 | n/a |
| FY Dec 2022 | n/a |
| FY Dec 2021 | n/a |
| Jun 2026 | n/a |
| Mar 2026 | n/a |
| Dec 2025 | n/a |
| Sep 2025 | n/a |
| Jun 2025 | n/a |
| Mar 2025 | n/a |
| Dec 2024 | n/a |
| Sep 2024 | n/a |
At each fiscal year end
Trailing four quarters at each quarter end
Return on equity
-14.4%
TTM net income over average of 2025-06-30 and 2026-06-30
Return on equity PRTA
| FY Dec 2025 | -63.6% |
| FY Dec 2024 | -23.3% |
| FY Dec 2023 | -24.8% |
| FY Dec 2022 | -21.5% |
| FY Dec 2021 | +20.6% |
| Jun 2026 | -14.4% |
| Mar 2026 | -40.3% |
| Dec 2025 | -63.6% |
| Sep 2025 | -67.6% |
| Jun 2025 | -66.9% |
| Mar 2025 | -23.5% |
| Dec 2024 | -23.3% |
| Sep 2024 | -22.9% |
At each fiscal year end
Trailing four quarters at each quarter end
Return on assets
-12.5%
TTM net income over average of 2025-06-30 and 2026-06-30
Return on assets PRTA
| FY Dec 2025 | -55.9% |
| FY Dec 2024 | -19.7% |
| FY Dec 2023 | -20.2% |
| FY Dec 2022 | -17.1% |
| FY Dec 2021 | +14.2% |
| Jun 2026 | -12.5% |
| Mar 2026 | -35.8% |
| Dec 2025 | -55.9% |
| Sep 2025 | -59.2% |
| Jun 2025 | -58.0% |
| Mar 2025 | -19.7% |
| Dec 2024 | -19.7% |
| Sep 2024 | -19.6% |
At each fiscal year end
Trailing four quarters at each quarter end
Return on invested capital
n/a
pre-tax loss, no effective tax rate to apply
Return on invested capital PRTA
| FY Dec 2025 | n/a |
| FY Dec 2024 | n/a |
| FY Dec 2023 | n/a |
| FY Dec 2022 | n/a |
| FY Dec 2021 | n/a |
| Jun 2026 | n/a |
| Mar 2026 | n/a |
| Dec 2025 | n/a |
| Sep 2025 | n/a |
| Jun 2025 | n/a |
| Mar 2025 | n/a |
| Dec 2024 | n/a |
| Sep 2024 | n/a |
At each fiscal year end
Trailing four quarters at each quarter end
Return on capital employed
-17.8%
operating income (EBIT proxy) over average of 2025-06-30 and 2026-06-30 minus current liabilities
Return on capital employed PRTA
| FY Dec 2025 | -54.7% |
| FY Dec 2024 | -27.2% |
| FY Dec 2023 | -28.4% |
| FY Dec 2022 | -20.5% |
| FY Dec 2021 | +16.3% |
| Jun 2026 | -17.8% |
| Mar 2026 | -31.1% |
| Dec 2025 | -54.7% |
| Sep 2025 | -60.1% |
| Jun 2025 | -60.6% |
| Mar 2025 | -27.0% |
| Dec 2024 | -27.2% |
| Sep 2024 | -27.1% |
At each fiscal year end
Trailing four quarters at each quarter end
P/E, trailing
n/a
trailing loss, a multiple of a loss is not meaningful
P/E, trailing PRTA
| FY Dec 2025 | n/a |
| FY Dec 2024 | n/a |
| FY Dec 2023 | n/a |
| FY Dec 2022 | n/a |
| FY Dec 2021 | 46.60x |
| Jun 2026 | n/a |
| Mar 2026 | n/a |
| Dec 2025 | n/a |
| Sep 2025 | n/a |
| Jun 2025 | n/a |
| Mar 2025 | n/a |
| Dec 2024 | n/a |
| Sep 2024 | n/a |
At each fiscal year end
Trailing four quarters at each quarter end
Enterprise value
n/a
no debt line filed
Enterprise value PRTA
| FY Dec 2025 | n/a |
| FY Dec 2024 | n/a |
| FY Dec 2023 | n/a |
| FY Dec 2022 | n/a |
| FY Dec 2021 | n/a |
| Jun 2026 | n/a |
| Mar 2026 | n/a |
| Dec 2025 | n/a |
| Sep 2025 | n/a |
| Jun 2025 | n/a |
| Mar 2025 | n/a |
| Dec 2024 | n/a |
| Sep 2024 | n/a |
At each fiscal year end
Trailing four quarters at each quarter end
FCF yield
-14.1%
TTM free cash flow over market value at close 2026-10-26
FCF yield PRTA
| FY Dec 2025 | -31.8% |
| FY Dec 2024 | -20.2% |
| FY Dec 2023 | -7.0% |
| FY Dec 2022 | -3.7% |
| FY Dec 2021 | +4.0% |
| Jun 2026 | -11.8% |
| Mar 2026 | -15.6% |
| Dec 2025 | -31.8% |
| Sep 2025 | -35.8% |
| Jun 2025 | -59.0% |
| Mar 2025 | -19.6% |
| Dec 2024 | -20.2% |
| Sep 2024 | -17.2% |
At each fiscal year end
Trailing four quarters at each quarter end
PEG, trailing
n/a
trailing loss, a multiple of a loss is not meaningful
PEG, trailing PRTA
| FY Dec 2025 | n/a |
| FY Dec 2024 | n/a |
| FY Dec 2023 | n/a |
| FY Dec 2022 | n/a |
| FY Dec 2021 | n/a |
| Jun 2026 | n/a |
| Mar 2026 | n/a |
| Dec 2025 | n/a |
| Sep 2025 | n/a |
| Jun 2025 | n/a |
| Mar 2025 | n/a |
| Dec 2024 | n/a |
| Sep 2024 | n/a |
At each fiscal year end
Trailing four quarters at each quarter end
Price as of 2026-10-26. Hover or tap a tile for its yearly and quarterly history.
Method
TTM is four consecutive fiscal quarters; Q4 is the year minus nine months when not filed. Returns use the average of opening and closing balances. EBIT is approximated by operating income. PEG uses trailing EPS growth.
Fundamentals
Annual figures from XBRL filings. Pick a past date to see them as known then.
| 2025-12 | 2024-12 | 2023-12 | 2022-12 | |
|---|---|---|---|---|
| Revenue | $9.7M | $135.2M | $91.4M | $53.9M |
| Operating income | -$214.6M | -$154.6M | -$191.0M | -$131.6M |
| Net income | -$244.1M | -$122.3M | -$147.0M | -$116.9M |
| EPS (diluted) | -4.53 | -2.27 | -2.76 | -2.47 |
| Operating cash flow | -$163.6M | -$150.1M | -$133.9M | -$108.8M |
| Cash | $307.5M | $471.4M | $618.8M | $710.4M |
SEC XBRL, fiscal years, as known on 2026-10-28
PRTA Stock Sonar score 4/7 axes
Find similar shapesComparePRTA ranks highest on insider conviction (76th percentile) and profitability (74th), and lowest on growth (10th), among Pharma & Biotech peers.
4 of 7 axes scored. Each is a percentile against sector peers (all companies when the sector is thin); higher is better. An unscored axis is unmeasured, not low. How it is scored
PRTA filings, in plain words
Are Prothena Corp Public insiders buying or selling PRTA?
In the 180 days to 2026-10-28, Prothena Corp Public insiders were net buyers, a net $11.9M: $12.1M of purchases and $136.0K of sales reported on Form 4, by 1 buyer and 2 sellers.
Are there planned insider sales of PRTA?
Yes. 2 Form 144 notices of planned insider sales were filed in the 90 days to 2026-10-28, covering $136.0K of stock; the latest, by MICHAEL JOHN ISAACS, was filed 2026-07-29.
Read the full summary
In the 180 days to 2026-10-28, Prothena Corp Public insiders were net buyers of PRTA, a net $11.9M across purchases and sales reported on Form 4 by 1 buyer and 2 sellers. Most of that figure, $12.1M, came from a holder of 10% or more rather than an officer or director. Purchases outweighed sales more than tenfold by value. Insiders filed 2 Form 144 notices of intent to sell in the 90 days to 2026-10-28, covering $136.0K of stock. Each figure is counted from SEC and House filings as of 2026-10-28, dated the day the filing was made public.
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