The cluster is entirely passive rebalancing — Vanguard, BlackRock, and State Street adding reflects index fund inflows, not a fundamental thesis. Monitor for active manager or insider buying as a stronger signal.
Executive Summary
Five mega-passive institutional investors (Vanguard, BlackRock, State Street, Morgan Stanley, BofA) all increased their positions in Assembly Biosciences during Q3 2025, adding a net $12.0M in new holdings. The cluster is entirely passive/index-driven, reflecting broad-based rebalancing rather than an active investment thesis.
Key Financial Metrics
Institutional Positions
Net institutional flow: $12.0M
▲ Buyers (5)
| Institution | Action | Change | Position Value | Value Δ |
|---|---|---|---|---|
| Vanguard | ADD | +97.8% | $12.9M | $8.3M |
| BlackRock | ADD | +89.8% | $4.4M | $2.7M |
| State Street | ADD | +59.9% | $1.1M | $893.0K |
| Morgan Stanley | ADD | +64.1% | $90.0K | $51.0K |
| BofA | DOUBLED | +6382.7% | $86.0K | $85.0K |
Key Facts
- 5 institutions added $12.0M net to ASMB positions in Q3 2025, all mega-passive funds (Vanguard, BlackRock, State Street, Morgan Stanley, BofA)
- No sellers in the cluster — 100% same-direction buying
- Vanguard added the most in absolute terms: +$8.3M (97.8% share increase)
- BofA nearly doubled from a tiny base (52 → 3,384 shares, +6,382.7%)
- All buyers are passive/index funds — no active managers, hedge funds, or activists participated
Financial Impact
5 institutions accumulated $12.0M in new ASMB positions during Q3 2025, bringing total disclosed holdings to $18.5M
Risk Factors
- 13F data is 45+ days stale — positions may have been unwound since quarter-end
- Passive buying does not reflect conviction; index rebalancing can reverse next quarter
- Historical underperformance of ASMB following prior signals suggests continued downside risk
Market Snapshot
Investment Themes
Documents Analyzed
This report is based on 1 institutional 13F filing from SEC EDGAR.
| Document | Accession Number |
|---|---|
| INST-CLUSTER Data (Synthetic) | inst-cluster-ASMB-2025-Q3 |
Filters
| Type | Now | ||||
|---|---|---|---|---|---|
Aug 15, 2026 10w ago | Institutional Cluster | $30.01 $35.28 | ▲ +17.56% | ▲ +18.75% | — |
Aug 13, 2026 10w ago | Press Release | $32.95 $34.38 | ▲ +4.34% | ▲ +5.71% | — |
Jun 11, 2026 19w ago | Institutional Cluster | $22.53 $24.15 | ▲ +7.19% | ▲ +6.76% | — |
Jun 5, 2026 20w ago | 8-K | $22.56 $23.34 | ▲ +3.48% | ▲ +1.37% | — |
May 22, 2026 22w ago | 424B5 | $28.75 $26.92 | ▲ +6.37% | ▲ +7.45% | — |
May 22, 2026 22w ago | 8-K | $28.34 $26.92 | ▼ −5.01% | ▼ −6.67% | — |
May 22, 2026 22w ago | Press Release | $28.34 $26.92 | ▼ −5.01% | ▼ −6.67% | — |
May 7, 2026 24w ago | Press Release | $29.74 $30.30 | ▲ +1.88% | ▲ +0.42% | — |
Mar 30, 2026 30w ago | EFFECT | $26.64 $28.53 | ▲ +7.09% | ▲ +2.79% | — |
Mar 19, 2026 31w ago | Press Release | $28.46 $27.70 | ▼ −2.67% | ▼ −0.52% | — |
US Market Status
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