Prothena Corporation plc (PRTA) — 13F Holders Deep Dive (Q2 2026)

PRTA ranks #3101 out of 37501 tracked stocks by institutional interest — one of the most closely watched names in our coverage.

192 institutions disclose a position in PRTA, but none treat it as a major bet — even Rangeley Capital, LLC, its most concentrated holder, allocates just 3.7% of its own portfolio to it.

Rubric Capital Management LP has added to its PRTA position for two straight quarters, increasing it by $13.8M to reach $49.0M today.

Jane Street Group, LLC has trimmed its PRTA position for two straight quarters, cutting it by $5.2M while still holding $1.5M.

PRTA is down 1.7% today, but institutions show net buying of $25.9M this quarter — a divergence between today's price move and the underlying institutional flow.

PRTA reported a net loss of $44.0M over the trailing twelve months.

• Not yet profitable — net loss of $44.0M over the trailing twelve months
• Revenue grew 427.3% year over year
• Net income improved year over year, from -$302.9M to -$44.0M
• Operating cash flow was negative, using $163.6M in cash
• Current ratio of 7.72x — enough short-term assets to cover short-term liabilities
• Liabilities run 0.17x equity — within a conventional range