Prothena stock falls to USD 8.51 as earnings beat estimates

Published on 09/22/2026 at 12:38 | Editorial responsibility: Rafael Müller, Editor-in-Chief AD HOC NEWS

Prothena stock traded at USD 8.51 on September 21, 2026, with a USD 445.50 million market value. Quarterly EPS beat estimates by USD 0.07.

PRTA, IE00B91XRN20, Illustration mit AI erstellt.

Prothena Corporation plc stock (ISIN IE00B91XRN20) closed at USD 8.51 on Nasdaq on September 21, 2026, down USD 0.07, while its market capitalization stood at USD 445.50 million. The biotechnology company is trading below its 52-week high of USD 11.80 and above its 52-week low of USD 7.73.

Quarterly loss beats estimates

According to MarketBeat on September 21, 2026, Prothena reported a quarterly loss of USD 0.32 per share for the quarter announced on August 6, 2026. That result was USD 0.07 better than the analyst consensus loss of USD 0.39 per share.

Revenue reached USD 1.01 million in the same quarter, compared with analyst estimates of USD 0.42 million, a USD 0.59 million difference. The comparison matters because Prothena's earnings remain loss-making, making revenue delivery and research progress important reference points for the stock valuation.

Trading range keeps risk visible

MarketBeat data cited on September 21, 2026, showed trading volume of 360,687 shares against an average volume of 507,159 shares. The stock's 50-day moving average was USD 8.91 and its 200-day moving average was USD 9.41, placing the September 21 close below both reference levels.

The broader valuation picture remains demanding: the reported price-to-earnings ratio was negative 10.13, while the PEG ratio was 3.02. Prothena also recorded a negative net margin of 80.68 percent for the reported period, so the USD 1.01 million quarterly revenue figure does not yet translate into profitability.

Consensus target remains higher

According to MarketBeat on September 21, 2026, analysts had a consensus rating of Moderate Buy and a consensus price target of USD 24.57. That target is USD 16.06 above the September 21 closing price, but the comparison is accompanied by a current-year consensus forecast of negative USD 0.08 earnings per share.

Prothena stock closes at USD 8.51

Prothena stock closed at USD 8.51 on Nasdaq on September 21, 2026, after changing by negative USD 0.07 on the session. Its reported 52-week range of USD 7.73 to USD 11.80 and market capitalization of USD 445.50 million provide the current market frame.