Who owns SION? 13F holders and whale ownership
SION is tracked across public portfolios in Whale Analyzer. This page answers who owns SION, which top funds are buying SION, aggregate disclosed value, and recent position changes based on public data. Peter Kolchinsky is the largest reported holder at $397M; the top five funds control 100.0% of reported ownership; institutions were net selling last quarter (0 increased, 2 reduced); the stock trades above the aggregate whale cost basis of $9.0. Top tracked holders include Peter Kolchinsky, Samuel Isaly, Andreas Halvorsen, and Joseph Edelman.
Continue to the live SION dashboardTop holders
| Investor | Reported value | Shares | Change |
|---|---|---|---|
| Peter Kolchinsky 13F portfolio RA Capital Management holdings | $397.1M | 9.9M | Held |
| Samuel Isaly 13F portfolio OrbiMed Advisors holdings | $141.5M | 3.5M | Reduced |
| Andreas Halvorsen 13F portfolio Viking Global Investors holdings | $128.1M | 3.2M | Held |
| Joseph Edelman 13F portfolio Perceptive Advisors holdings | $26.4M | 658.4K | Reduced |
| Baker Bros. Advisors 13F portfolio Baker Bros. Advisors holdings | $16.0M | 400.0K | Held |
Ownership concentration
Reported ownership of SION is highly concentrated across tracked institutions.
- Single largest holder: 56.0% of reported ownership
- Top 5 holders: 100.0%
- Top 10 holders: 100.0%
Whale activity this quarter
Across 5 tracked institutions, 3 held, 2 reduced. Net positioning is net selling.
- Peter Kolchinsky — RA Capital Management ($397.1M) (→ 0.0% qoq shares) · avg cost $8.61
- Samuel Isaly — OrbiMed Advisors ($141.5M) (▼ 0.9% qoq shares) · avg cost $8.79
- Andreas Halvorsen — Viking Global Investors ($128.1M) (→ 0.0% qoq shares) · avg cost $10.25
- Joseph Edelman — Perceptive Advisors ($26.4M) (▼ 44.2% qoq shares)
- Baker Bros. Advisors — Baker Bros. Advisors ($16.0M) (→ 0.0% qoq shares) · avg cost $10.46
Whale cost basis vs current price
The aggregate tracked cost basis is $9.00 versus a current price of $42.18, so SION trades above its cost basis (+368.8%). Average unrealized P&L across tracked holders: 318%.
Sector positioning — Health Care
SION sits within the Health Care sector alongside 221 other tracked names. Compare whale ownership across peers:
How to use this page
Values are reported public positions from tracked 13F filers and disclosures — not real-time ownership totals. Open the live SION dashboard for price charts and cross-investor scans, or read the SEC 13F guide.
Related stock holder pages
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- TYRA whale holders — TYRA BIOSCIENCES INC
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- NUVL whale holders — NUVALENT INC-A
- DNTH whale holders — DIANTHUS THERAPEUTICS INC
Learn more in Whale Analyzer Academy
Deepen your read on SION with these Whale Analyzer Academy guides:
Frequently asked questions
Who owns SION stock?
Whale Analyzer tracks 5 public institutional holders of SION with a combined reported value of $709.2M. See the holder table above for the largest tracked positions.
Which top funds are buying SION?
Tracked institutions were net selling last quarter — 3 held, 2 reduced. Check the "Change" column: "New" = fresh position, "Increased" = added, "Reduced" = trimmed.
How concentrated is SION ownership?
The top five tracked holders report 100.0% of aggregate ownership.
Is SION above or below the whale cost basis?
The aggregate tracked cost basis is $9.00 versus a current price of $42.18 (+368.8%).
What does 13F ownership mean for SION?
Use the interactive SION dashboard on Whale Analyzer for real-time holder analysis, or read our 13F Alpha Signals Guide.