PRTAProthena Corporation plc

$8.21-17% 1Y

What is the market doing?

Mixed

No clear lean: insiders net buying, but in a downtrend (−11% vs 200-day) and a crowded short (+16% of shares).

1 good, 2 to watch
TrendDowntrendderived · Oct 23, 2026

In a downtrend, below its 50- and 200-day averages. Price is −11% vs its 200-day average.

Insider conviction+$2.7M (90 days to Oct 22, 2026)SEC EDGAR · Oct 22, 2026

Insiders were net buyers over the 90 days ending Oct 22, 2026.

Short interest16% of sharesFINRA · Sep 30, 2026

A crowded short, settled Sep 30, 2026, more than a week of normal trading to cover, a crowded exit.

Where this answer is blind. Insider selling is often routine (taxes, diversification); only cluster buying is a strong tell.

How PRTA is trading

Prothena Corporation plc is −17% over the past year while the S&P 500 is +16%: 33 points behind the market. Through the fall, its own insiders bought $5.8M more stock than they sold.

−17%

1-year return · S&P 500 +16%

vs 200-day average
−11%

vs 200-day average · a clear downtrend

RSI (14)
49

RSI (14) · neutral

Below its 52-week high
29%

Below its 52-week high

Oct 21, 2024$4.58 – $23.45 · dashed line: 200-day averageOct 23, 2026
Details›
Last close2026-10-23
$8.21
1 monthS&P 500 −0.94%
−1.6%
1 yearS&P 500 +16%
−17%
5 yearsS&P 500 +86%
−87%
vs 50-day average$8.79
−6.6%
52-week high
$11.51
52-week low
$7.91
Annualised volatility
65%
Insider buying, net, 6 monthsForms 3/4/5 to 2026-10-22
$5.8M
Calendar-year price return
YearReturn
2026 (year to date)−14%
2025−31%
2024−62%
2023−40%
2022+22%
2021+311%
2020−24%
2019+54%
2018−73%
2017−24%
Average return by calendar month, 2016–2026
MonthYearsPositiveAverage
Jan103 of 10−6.9%
Feb105 of 10+11%
Mar105 of 10−2.0%
Apr104 of 10−12%
May104 of 10−3.5%
Jun106 of 10+13%
Jul118 of 11+9.1%
Aug115 of 11+1.6%
Sep115 of 11+7.5%
Oct115 of 11−4.2%
Nov104 of 10+2.2%
Dec103 of 10−4.0%

End-of-day closes from IEX; the S&P 500 comparison uses SPY over the same window. Prices are a reference point, not a basis for trading decisions.

Where the price stands

Its trend against the 50-day and 200-day averages, and the levels it keeps coming back to.

What it has returned

With dividends, year by year, month by month, and by calendar month on average.