Whale Analyzer
BIIB Institutional Holders and 13F Ownership
Compare 8 tracked holders of BIIB, their reported positions and disclosed changes. Coverage is limited to the investors tracked by Whale Analyzer; these records do not establish all shareholders or current trades. Available original SEC filings for tracked 13F holders are linked below. Top tracked holders include PRIMECAP Management Company, National Pension Service, Patient Capital Management, and Causeway Capital Management.
Continue to the live BIIB dashboardTop holders
| Investor | Reported value | Shares | Change | Report date |
|---|---|---|---|---|
| PRIMECAP Management Company 13F holdings | $3.27B | 15.2M | Increased | 2026-06-30 |
| National Pension Service 13F holdings | $87.7M | 406.1K | Increased | 2026-06-30 |
| Patient Capital Management 13F holdings | $61.3M | 283.7K | Reduced | 2026-06-30 |
| Causeway Capital Management 13F holdings | $60.1M | 278.3K | Reduced | 2026-06-30 |
| Perceptive Advisors 13F holdings | $59.7M | 276.2K | New | 2026-06-30 |
| OrbiMed Advisors 13F holdings | $13.3M | 61.6K | Held | 2026-06-30 |
| Hillman Capital Management 13F holdings | $5.2M | 24.0K | Reduced | 2026-06-30 |
| Horizon Kinetics Asset Management 13F holdings | $589.0K | 2.7K | Reduced | 2026-06-30 |
Original SEC filing sources
These recorded filings support the tracked 13F rows included in the aggregate reported values on this page. See each holder profile for source coverage and context for other disclosure types.
- PRIMECAP Management Company SEC filing (0000763212-26-000028) · report date 2026-06-30
- National Pension Service SEC filing (0001193125-26-347818) · report date 2026-06-30
- Patient Capital Management SEC filing (0001854794-26-000005) · report date 2026-06-30
- Causeway Capital Management SEC filing (0000945621-26-001052) · report date 2026-06-30
- Perceptive Advisors SEC filing (0001012975-26-000777) · report date 2026-06-30
- OrbiMed Advisors SEC filing (0001172661-26-003740) · report date 2026-06-30
- Hillman Capital Management SEC filing (0001398344-26-014467) · report date 2026-06-30
- Horizon Kinetics Asset Management SEC filing (0001398344-26-014047) · report date 2026-06-30
Tracked-sample concentration
Reported position value for BIIB is highly concentrated within this tracked-holder sample. These percentages are not market-wide ownership shares.
- Largest tracked holder: 91.9% of aggregate reported value in this sample
- Top 5 tracked holders: 99.5% of aggregate reported value in this sample
- Top 10 tracked holders: 100.0% of aggregate reported value in this sample
Whale activity this quarter
Across 8 tracked holders, 4 reduced, 3 increased, 1 held. Net positioning is net selling.
- PRIMECAP Management Company ($3.27B) (▲ 2.7% qoq shares) · modeled avg cost estimate $243.89
- National Pension Service ($87.7M) (▲ 1.1% qoq shares) · modeled avg cost estimate $246.10
- Patient Capital Management ($61.3M) (▼ 25.3% qoq shares)
- Causeway Capital Management ($60.1M) (▼ 0.9% qoq shares)
- Perceptive Advisors ($59.7M) · modeled avg cost estimate $173.84
- OrbiMed Advisors ($13.3M) (→ 0.0% qoq shares)
- Hillman Capital Management ($5.2M) (▼ 18.8% qoq shares)
- Horizon Kinetics Asset Management ($589.0K) (▼ 4.6% qoq shares) · modeled avg cost estimate $179.58
Modeled cost estimate vs current price
The share-weighted modeled cost estimate across 4 covered tracked holders is $242.71 versus a current price of $248.35, so BIIB trades above that estimate (+2.3%). This model does not establish any filer's actual purchase price, unrealized gain, or investment return.
Sector positioning — Other
BIIB sits within the Other sector alongside 1558 other tracked names. Compare reported positions across tracked peers:
How to use this page
Values are reported public positions from tracked 13F filers and disclosures — not real-time or market-wide ownership totals. Open the live BIIB dashboard for price charts and cross-investor scans, or read the SEC 13F guide.
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Learn more in Whale Analyzer Academy
Deepen your read on BIIB with these Whale Analyzer Academy guides:
Frequently asked questions
Who owns BIIB stock?
Whale Analyzer tracks 8 public-disclosure holders of BIIB with a combined reported value of $3.56B. See the holder table above for the largest tracked positions.
Which top funds are buying BIIB?
Tracked holders were net selling last quarter — 4 reduced, 3 increased, 1 held. Check the "Change" column: "New" = fresh position, "Increased" = added, "Reduced" = trimmed.
How concentrated is the tracked BIIB sample?
The top five tracked holders account for 99.5% of aggregate reported value in this tracked sample. This is not a market-wide ownership percentage.
How does BIIB compare with the modeled cost estimate?
The share-weighted modeled cost estimate across 4 covered tracked holders is $242.71 versus a current price of $248.35 (+2.3%). It is not an actual purchase price, unrealized gain, or investment return.
What does 13F ownership mean for BIIB?
These are historical reported positions from tracked filers, not real-time ownership or a complete shareholder register. Use the interactive BIIB dashboard to explore them, or read our 13F Alpha Signals Guide.