Amphastar Pharmaceuticals
AMPH
235 hedge funds and large institutions have $900M invested in Amphastar Pharmaceuticals in 2025 Q4 according to their latest regulatory filings, with 26 funds opening new positions, 94 increasing their positions, 87 reducing their positions, and 33 closing their positions.
241% more call options, than puts
Call options by funds: $739K | Put options by funds: $217K
2.63% more ownership
Funds ownership: 70.43% → 73.07% (+2.6%)
8% more repeat investments, than reductions
Existing positions increased: 94 | Existing positions reduced: 87
3% more capital invested
Capital invested by funds: $873M → $900M (+$26.7M)
3% less funds holding
Funds holding: 243 → 235 (-8)
21% less first-time investments, than exits
New positions opened: 26 | Existing positions closed: 33
Top Buyers
| Rank | Fund | Capital Flow |
|---|---|---|
| 1 |
American Century Companies
Kansas City,
Missouri
|
+$9.7M |
| 2 |
Marshall Wace
London,
United Kingdom
|
+$9.36M |
| 3 |
Goldman Sachs
New York
|
+$8.13M |
| 4 |
Pacer Advisors
Malvern,
Pennsylvania
|
+$4.42M |
| 5 |
Arrowstreet Capital
Boston,
Massachusetts
|
+$4.3M |
Top Sellers
| Rank | Fund | Capital Flow |
|---|---|---|
| 1 |
Millennium Management
New York
|
-$10.5M |
| 2 |
AG
Algert Global
San Francisco,
California
|
-$6.9M |
| 3 |
T. Rowe Price Associates
Baltimore,
Maryland
|
-$6.14M |
| 4 |
Qube Research & Technologies (QRT)
London,
United Kingdom
|
-$3.34M |
| 5 |
BNP Paribas Financial Markets
Paris,
France
|
-$2.6M |
AMPH Hedge Fund Activity: Q4 2025 in Review
235 of the 8,267 institutional investors tracked by Wall St. Rank reported a position in Amphastar Pharmaceuticals (AMPH) for Q4 2025, worth a combined $900M — up 3.1% from $873M a quarter earlier.
Sellers outnumbered buyers: 33 funds closed out of AMPH and 26 opened new positions — a net loss of 7 holders — while 87 trimmed existing stakes and 94 added.
The largest buyer was American Century Companies, adding an estimated $9.7M. The largest seller was Millennium Management, cutting an estimated $10.5M.
- 235 institutional investors held Amphastar Pharmaceuticals (AMPH) as of Q4 2025, down from 243 in Q3 2025.
- Funds reported $900M of Amphastar Pharmaceuticals stock for Q4 2025, up 3.1% quarter-over-quarter.
- 26 funds opened new Amphastar Pharmaceuticals positions in Q4 2025 and 33 closed out, a net change of -7 holders.
- The largest Amphastar Pharmaceuticals buyer in Q4 2025 was American Century Companies, an estimated $9.7M added.
- The largest Amphastar Pharmaceuticals seller in Q4 2025 was Millennium Management, an estimated $10.5M sold.
Based on aggregated 13F filings for Q4 2025.