Ticker · CUSIP 829401108
Holders (tracked)
7
Combined shares
5,244,914
Combined value
$215.78M
Last close
$43.54
Quarter
2025Q4
Price · 1Y$43.54+32.47 (+293.32%)H $45.24 · L $11.07 · Avg Vol 266K
Insider sellPosition opened
Tracked holders · last 8 quarters
+1 vs previous quarter over the last 4.
Price is +5.8% vs the avg quarter-end implied price across tracked holders.
SEC event timeline
17 events
- ORBIMED ADVISORS LLC2026-04-16Sold $10.29M @ $45.34Insider sell
- Thompson Peter A.2026-04-16Sold $10.29M @ $45.34Insider sell
- Thompson Peter A.2026-04-15Sold $10.53M @ $44.64Insider sell
- ORBIMED ADVISORS LLC2026-04-15Sold $10.53M @ $44.64Insider sell
- ORBIMED ADVISORS LLC2026-04-14Sold $2.13M @ $44.51Insider sell
- Thompson Peter A.2026-04-14Sold $2.13M @ $44.51Insider sell
- D.E. Shaw & Co. opened position2026-02-17+5,742 shares · 2025Q4Position
- Two Sigma Investments opened position2026-02-17+6,400 shares · 2025Q4Position
- Ken Griffin (Citadel Advisors) added2026-02-17+1,051,402 shares · 2025Q4Position
- Izzy Englander (Millennium Mgmt) trimmed2026-02-17−133,539 shares · 2025Q4Position
- T. Rowe Price added2026-02-17+193,613 shares · 2025Q4Position
- Wellington Management trimmed2026-02-17−3,887 shares · 2025Q4Position
- Renaissance Technologies exited2026-02-12−14,600 shares · 2025Q4Position
- Wellington Management opened position2025-11-14+42,234 shares · 2025Q3Position
- Izzy Englander (Millennium Mgmt) added2025-11-14+200,051 shares · 2025Q3Position
- T. Rowe Price trimmed2025-11-14−223,478 shares · 2025Q3Position
- Renaissance Technologies trimmed2025-11-13−11,400 shares · 2025Q3Position
Insider activity
Last 30 days
Net (open-market)
−$45.89M
Buys
0 · $0
Sells
6 · $45.89M
Unique insiders
2
| Date | Insider | Code | Shares | Price | Value |
|---|---|---|---|---|---|
| 04-16 | ORBIMED ADVISORS LLC Director | S | 226,906 | $45.34 | $10.29M |
| 04-16 | Thompson Peter A. Director | S | 226,906 | $45.34 | $10.29M |
| 04-15 | Thompson Peter A. Director | S | 235,863 | $44.64 | $10.53M |
| 04-15 | ORBIMED ADVISORS LLC Director | S | 235,863 | $44.64 | $10.53M |
| 04-14 | ORBIMED ADVISORS LLC Director | S | 47,814 | $44.51 | $2.13M |
| 04-14 | Thompson Peter A. Director | S | 47,814 | $44.51 | $2.13M |
Follow-the-investor returns
If you'd copied each holder of SION…
Cost basis inferred from each manager's quarter-over-quarter position changes. Sorted by % return on the position they're still holding.
| Investor | First in | Cost basis | Return | Position value today |
|---|---|---|---|---|
| Two Sigma Investments | 2025Q1 | $10.46 | +316.3% | $279K |
| Andreas Halvorsen (Viking Global) | 2025Q1 | $10.98 | +296.4% | $139.1M |
| T. Rowe Price | 2025Q1 | $17.61 | +147.3% | $36.2M |
| Izzy Englander (Millennium Mgmt) | 2025Q1 | $28.17 | +54.6% | $3.5M |
| Wellington Management | 2025Q3 | $29.41 | +48.0% | $1.7M |
| Ken Griffin (Citadel Advisors) | 2025Q1 | $40.13 | +8.5% | $47.3M |
| D.E. Shaw & Co. | 2025Q4 | $41.14 | +5.8% | $250K |
Who moved on this name in 2025Q4
Position changes reported for the latest quarter, grouped by direction.
New positions2
- Two Sigma Investments+6,400$263K
- D.E. Shaw & Co.+5,742$236K
Added to2
- Ken Griffin (Citadel Advisors)+1,051,402$43.3M
- T. Rowe Price+193,613$8K
Trimmed2
- Izzy Englander (Millennium Mgmt)−133,539$5.5M
- Wellington Management−3,887$160K
Exited1
- Renaissance Technologies−14,600$429K
Institutional ownership over time
Distinct super-investors holding this ticker · combined dollar value, by quarter.
| Quarter | Holders | Combined value |
|---|---|---|
| 2025Q1 | 5 | $46.7M |
| 2025Q2 | 5 | $73.3M |
| 2025Q3 | 6 | $121.8M |
| 2025Q4 | 7 | $215.8M |
Who owns SION
7 super-investors · 2025Q4
Tracked stake
5.24M
shares
Combined value
$216M
% of shares outstanding
—
shares-out unknown
Quarter action mix
New2Added2Trim2Held1
| # | Manager | Shares | Value |
|---|---|---|---|
| 1 | Andreas Halvorsen Viking Global | 3.20M | $131M |
| 2 | Ken Griffin Citadel Advisors | 1.09M | $45M |
| 3 | T. Rowe Price | 831.4K | $34M |
| 4 | Izzy Englander Millennium Mgmt | 80.5K | $3M |
| 5 | Wellington Management | 38.3K | $2M |
| 6 | Two Sigma Investments | 6.4K | $263K |
| 7 | D.E. Shaw & Co. | 5.7K | $236K |
Recent moves
20 transactions
- +1,051,402 · 2025Q4
- +5,742 · 2025Q4
- +6,400 · 2025Q4
- −3,887 · 2025Q4
- −133,539 · 2025Q4
- +193,613 · 2025Q4
- −14,600 · 2025Q4
- +42,234 · 2025Q3
- +200,051 · 2025Q3
- TRIMT. Rowe Price−223,478 · 2025Q3
- −11,400 · 2025Q3
- −165,038 · 2025Q2
- TRIMT. Rowe Price−134,974 · 2025Q2
- −11,715 · 2025Q2
- +242,427 · 2025Q2
- +26,000 · 2025Q2
- +179,072 · 2025Q1
- +11,715 · 2025Q1
- +2,952,754 · 2025Q1
- +996,212 · 2025Q1
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