Insider Buying: Prothena (NASDAQ:PRTA) Major Shareholder Acquires $981,000.00 in Stock

Posted by Brian Himes on May 29th, 2026

Prothena Corporation plc (NASDAQ:PRTA – Get Free Report) major shareholder William Scully bought 100,000 shares of the stock in a transaction on Friday, May 22nd. The stock was purchased at an average price of $9.81 per share, for a total transaction of $981,000.00. Following the purchase, the insider directly owned 836,000 shares of the company’s stock, valued at approximately $8,201,160. This represents a 13.59% increase in their ownership of the stock. The purchase was disclosed in a document filed with the Securities & Exchange Commission, which is available at this link. Major shareholders that own more than 10% of a company’s stock are required to disclose their sales and purchases with the SEC.

Prothena Price Performance

Shares of PRTA stock opened at $9.98 on Friday. Prothena Corporation plc has a fifty-two week low of $4.42 and a fifty-two week high of $11.80. The stock’s 50-day moving average is $10.05 and its two-hundred day moving average is $9.75. The firm has a market cap of $522.45 million, a P/E ratio of -3.54, a PEG ratio of 1.60 and a beta of -0.23.

Prothena (NASDAQ:PRTA – Get Free Report) last announced its quarterly earnings results on Thursday, May 7th. The biotechnology company reported $0.60 EPS for the quarter, beating the consensus estimate of ($0.31) by $0.91. The business had revenue of $51.08 million during the quarter, compared to analysts’ expectations of $0.81 million. Prothena had a negative return on equity of 43.44% and a negative net margin of 260.92%. As a group, research analysts expect that Prothena Corporation plc will post 0.18 EPS for the current year.

Hedge Funds Weigh In On Prothena

Several hedge funds and other institutional investors have recently added to or reduced their stakes in the stock. Rubric Capital Management LP grew its holdings in Prothena by 36.0% during the first quarter. Rubric Capital Management LP now owns 5,000,000 shares of the biotechnology company’s stock valued at $48,600,000 after purchasing an additional 1,322,669 shares during the last quarter. State Street Corp boosted its holdings in Prothena by 151.7% during the fourth quarter. State Street Corp now owns 2,267,802 shares of the biotechnology company’s stock valued at $21,658,000 after acquiring an additional 1,366,764 shares during the period. ADAR1 Capital Management LLC boosted its holdings in Prothena by 8.5% during the first quarter. ADAR1 Capital Management LLC now owns 1,581,443 shares of the biotechnology company’s stock valued at $15,372,000 after acquiring an additional 123,679 shares during the period. Palo Alto Investors LP boosted its holdings in Prothena by 3.9% during the third quarter. Palo Alto Investors LP now owns 1,324,028 shares of the biotechnology company’s stock valued at $12,923,000 after acquiring an additional 49,275 shares during the period. Finally, Geode Capital Management LLC boosted its holdings in Prothena by 4.3% during the fourth quarter. Geode Capital Management LLC now owns 1,063,069 shares of the biotechnology company’s stock valued at $10,154,000 after acquiring an additional 43,586 shares during the period. Institutional investors and hedge funds own 97.08% of the company’s stock.

Wall Street Analysts Forecast Growth

Several equities analysts recently weighed in on PRTA shares. Weiss Ratings raised shares of Prothena from a “sell (e+)” rating to a “sell (d-)” rating in a research report on Thursday, May 14th. Stifel Nicolaus set a $19.00 price objective on shares of Prothena in a research report on Friday, March 13th. Royal Bank Of Canada raised their price objective on shares of Prothena from $11.00 to $12.00 and gave the company a “sector perform” rating in a research report on Friday, February 20th. Citizens Jmp raised their price objective on shares of Prothena from $19.00 to $20.00 and gave the company a “market outperform” rating in a research report on Friday, May 8th. Finally, Citigroup reaffirmed an “outperform” rating on shares of Prothena in a research report on Friday, May 8th. One research analyst has rated the stock with a Strong Buy rating, four have given a Buy rating, two have given a Hold rating and one has given a Sell rating to the company’s stock. According to MarketBeat.com, the company currently has a consensus rating of “Moderate Buy” and a consensus target price of $23.75.

Check Out Our Latest Research Report on Prothena

About Prothena

(Get Free Report)

Prothena Corporation plc is a clinical-stage biotechnology company dedicated to the discovery and development of novel therapies for neurodegenerative and rare diseases driven by misfolded proteins. The company’s research focuses on immunotherapies and small molecules designed to target and clear disease-causing protein aggregates. Prothena leverages proprietary protein engineering and antibody discovery platforms to advance candidates through preclinical and clinical stages.

The company’s most advanced program is an antibody targeting aggregated alpha-synuclein for the potential treatment of Parkinson’s disease, currently in mid-stage clinical trials.