ANNX Annexon, Inc.
Executive Summary
A bullish institutional cluster formed in ANNX during Q3 2025, with 5 buyers accumulating $9.8M in net new holdings versus 1 seller trimming $3.9M. The buying was dominated by Morgan Stanley (doubling to $9.2M) and Nuveen (doubling to $2.1M), alongside quant funds Citadel and Two Sigma. This signals growing conviction ahead of potential pipeline catalysts, though historical calibration shows long calls on ANNX have underperformed at T+20.
Key Financial Metrics
Institutional Positions
Net institutional flow: $5.9M
▲ Buyers (5)
| Institution | Action | Change | Position Value | Value Δ |
|---|---|---|---|---|
| Morgan Stanley | DOUBLED | +263.9% | $9.2M | $7.2M |
| Nuveen | DOUBLED | +166.7% | $2.1M | $1.5M |
| Citadel | DOUBLED | +1162.5% | $511.0K | $479.0K |
| Two Sigma | ADD | +38.8% | $851.0K | $369.0K |
| Invesco | ADD | +34.3% | $616.0K | $255.0K |
▼ Sellers (1)
| Institution | Action | Change | Prev Value | Value Δ |
|---|---|---|---|---|
| Fidelity | TRIM | -29.4% | $37.7M | -$3.9M |
Actionable Insight
The cluster suggests growing institutional interest ahead of potential clinical catalysts, but ANNX's historical T+20 performance on long calls has been poor (29% win rate, avg -1.14%). Monitor for upcoming pipeline data readouts or partnership announcements that could validate the thesis. The Fidelity trim is a cautionary signal given its size.
Key Facts
- 5 institutional buyers added $9.8M net, led by Morgan Stanley ($7.2M increase) and Nuveen ($1.5M increase)
- Citadel more than 10x'd its position (13.3K → 167.5K shares), a high-conviction quant entry
- Only 1 seller (Fidelity) trimmed 29.4% of its position, reducing by $3.9M
- Total buyer holdings reached $13.3M vs seller holdings of $33.8M (Fidelity remains the largest holder)
- Cluster includes 2 mega-passive, 2 quant, and 1 active asset manager — mixed signal quality
Financial Impact
5 institutions accumulated $9.8M in new positions while 1 institution reduced holdings by $3.9M, for a net institutional inflow of approximately $5.9M
Risk Factors
- Historical calibration shows long calls on ANNX underperform at T+20 (avg -1.14%, 29% win rate)
- Fidelity remains the dominant holder at $33.8M and trimmed — further selling could pressure the stock
- 13F data is 45+ days stale; positions may have already been adjusted
- Two of five buyers are passive/index funds (Invesco, Morgan Stanley), diluting the active signal
Market Snapshot
Documents Analyzed
This report is based on 1 institutional 13F filing from SEC EDGAR.
| Document | Accession Number |
|---|---|
| INST-CLUSTER Data (Synthetic) | inst-cluster-ANNX-2025-Q3 |
Filters
| Type | Now | ||||
|---|---|---|---|---|---|
|
Jun 12, 2026
1d ago
|
ANALYST-UPGRADE
| $5.88 awaiting T+5 | awaiting T+5 | — | — |
|
Jun 11, 2026
1d ago
|
Institutional Cluster
| $4.74 awaiting T+5 | awaiting T+5 | — | — |
|
May 16, 2026
27d ago
|
ANALYST-UPGRADE
| $5.11 $5.02 | ▼ −1.76% | ▼ −0.93% | — |
|
May 12, 2026
4w ago
|
ANALYST-UPGRADE
| $5.44 $4.96 | ▲ +8.82% | ▲ +8.90% | — |
|
May 7, 2026
5w ago
|
Press Release
| $5.69 $5.37 | ▼ −5.62% | ▼ −7.09% | — |
|
Apr 16, 2026
8w ago
|
ANALYST-UPGRADE
| $6.33 $6.06 | ▼ −4.27% | ▼ −5.25% | — |
|
Apr 16, 2026
8w ago
|
ANALYST-UPGRADE
| $6.33 $6.06 | ▼ −4.27% | ▼ −5.25% | — |
|
Mar 30, 2026
10w ago
|
Press Release
| $5.54 $6.05 | ▲ +9.21% | ▲ +5.26% | — |
|
Mar 2, 2026
14w ago
|
Insider Cluster
| $5.52 $5.59 | ▲ +1.27% | ▲ +2.48% | — |
US Market Status
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