RA Capital Management SION Position
Active8-Fund ConvergenceRA Capital Management trimmed their position in Sionna Therapeutics, Inc. (SION) in Q4 2025, holding $407.5M worth of shares across 9,905,045 shares.
The position was first reported in Q1 2025 and has been tracked across 4 quarterly 13F filings.
SION is a convergence signal: 8 specialist biotech funds hold this stock, suggesting high institutional conviction.
There is an upcoming Phase 2 readout for SION-719 in 106 days (Jul 31, 2026), making the timing of RA Capital's position particularly relevant.
Short interest stands at 13.1% of float with 15.1 days to cover, indicating significant bearish positioning against RA Capital's long thesis.
About Sionna Therapeutics, Inc.
Sionna Therapeutics, Inc. is a biopharmaceutical company. The Company provides treatment paradigm for cystic fibrosis patients by developing medicines that normalize the function of the cystic fibrosis transmembrane conductance regulator.
Full company profile →Short Interest
13.1%
15.1 days to cover
RA Capital Management SION Position History
Frequently Asked Questions
Does RA Capital Management own SION?
Yes. As of Q4 2025, RA Capital Management holds 9,905,045 shares of Sionna Therapeutics, Inc. (SION) valued at $407.5M. This data comes from their SEC 13F filing.
How many hedge funds own SION?
8 specialist biotech hedge funds currently hold SION, including OrbiMed Advisors, Perceptive Advisors, Deerfield Management and 4 more. When 3 or more specialist funds hold the same stock, BiotechEdge flags it as a convergence signal.
When did RA Capital Management first buy SION?
RA Capital Management's position in SION was first reported in Q1 2025. 13F filings are reported with a 45-day delay, so the actual purchase may have occurred earlier in the quarter.
Is RA Capital Management's SION position increasing or decreasing?
RA Capital Management trimmed their SION position in the most recent quarter, reducing by 540,277 shares.
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