Amphastar Pharmaceuticals, Inc.
US ˙ NasdaqGS ˙ US03209R1032

SecurityAMPH / Amphastar Pharmaceuticals, Inc.
InstitutionQuadrant Capital Group Llc
Latest Disclosed Ownership1,131 shares
Latest Disclosed Value $ 22,157
Quadrant Capital Group Llc reports 58.63% decrease in ownership of AMPH / Amphastar Pharmaceuticals, Inc.

On May 13, 2026 - Quadrant Capital Group Llc filed a 13F-HR/A form disclosing ownership of 1,131 shares of Amphastar Pharmaceuticals, Inc. (US:AMPH) valued at $22,156 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 12, 2026 disclosing 2,734 shares of Amphastar Pharmaceuticals, Inc.. This represents a change in shares of -58.63% during the quarter. The current value of the position is $21,150 USD.

Institutional Ownership: 13F and NPORT Filings

The Security and Class in the table below are shown exactly as filed by the investor. We do our best to track continuity of investments through acquisitions, and this will be reflected in the table as changes in names. In addition to descriptive data, performance of the investment is shown over time. To calculate quarterly performance, we first calculate cost basis of the shares purchased during the quarter, then use that to calculate gross profit. Quarterly return is Gross Profit / Starting Portfolio value.

Note that cost basis is calculated and stored in thousands, so small quarterly changes in shares frequently result in a cost basis of zero.

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Disclosed Equity Positions (from 13F/NPORT Filings)
File
Date		 Effective
Date		Form Security Class ID Avg Price
Paid (Est)		 Reported
Shares		 ΔShares ΔShares
(%)		 Reported
Value
(x1000)		 ΔValue
(%)		 Alloc
(%)		 ΔAlloc ΔAlloc (%) Cost Basis
(x1000)		 Unrealized
Gain/Loss
(x1000)
2026-05-13 2026-03-31 13F/A-1 AMPHASTAR PHARMACEUTICALS IN COM 03209R103 1,131 -1,603 -58.63 22 -69.86 0.0007
2026-05-11 2026-03-31 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 1,131 -1,603 49 0.0369
2026-02-12 2025-12-31 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 2,734 -342 -11.12 73 -9.88 0.0022
2025-11-13 2025-09-30 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 3,076 3,076 82 0.0027
2025-08-13 2025-06-30 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 0 -8,277 -100.00 0 -100.00
2025-05-13 2025-03-31 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 8,277 7,537 1,018.51 240 785.19 0.0089
2025-02-13 2024-12-31 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 740 0 0.00 27 -22.86 0.0019
2024-11-12 2024-09-30 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 740 -53 -6.68 36 12.90 0.0025
2024-08-12 2024-06-30 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 793 -10 -1.25 32 -11.43 0.0024
2024-05-15 2024-03-31 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 803 -223 -21.73 35 -44.44 0.0028
2024-02-08 2023-12-31 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 1,026 223 27.77 63 75.00 0.0055
2023-11-14 2023-09-30 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 803 -19 -2.31 37 -23.40 0.0037
2023-08-10 2023-06-30 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 822 10 1.23 47 56.67 0.0047
2023-05-11 2023-03-31 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 812 511 169.77 30 275.00 0.0032
2023-02-13 2022-12-31 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 301 -103 -25.50 8 -27.27 0.0010
2022-11-10 2022-09-30 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 404 177 77.97 11 37.50 0.0015
2022-08-09 2022-06-30 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 227 -167 -42.39 8 -42.86 0.0011
2022-05-06 2022-03-31 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 394 149 60.82 14 133.33 0.0017
2022-02-01 2021-12-31 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 245 -111 -31.18 6 -14.29 0.0007
2021-11-12 2021-09-30 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 356 248 229.63 7 250.00 0.0010
2021-08-09 2021-06-30 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 108 -10 -8.47 2 0.00 0.0003
2021-05-12 2021-03-31 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 118 63 114.55 2 100.00 0.0003
2021-02-16 2020-12-31 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 55 0 0.00 1 0.00 0.0002
2020-11-13 2020-09-30 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 55 0 0.00 1 0.00 0.0002
2020-08-13 2020-06-30 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 55 0 0.00 1 0.00 0.0002
2020-05-15 2020-03-31 13F Amphastar Pharmaceuticals Inc Del Com Com 03209R103 55 55 1 0.0002
2019-10-24 2019-09-30 13F Amphastar Pharmaceuticals Inc Del Com COM 03209R103 0 -2,636 -100.00 0 -100.00
2019-07-24 2019-06-30 13F Amphastar Pharmaceuticals Inc Del Com COM 03209R103 2,636 0 0.00 54 1.89 0.0085
2019-04-29 2019-03-31 13F Amphastar Pharmaceuticals Inc Del Com COM 03209R103 2,636 2,636 53 0.0093
Legend
Shares
The total number of shares held by the institution at the end of the reporting period (the effective date). This is provided in the filing.
Value
The total value of the shares as of the effective date. This is provided in the filing.
Avg. Share Price
The weighted average share price of the shares held by the institution. We use FIFO accounting to determine this price
Class
This is the security class as indicated by the filer. There are a variety of values for this field. Common values include "EC" = equity common, "EP" - equity preferred
Allocation (%)
The percent of the institution's portfolio that this position represents. This is provided in NPORT filings. For 13F filings, we calculate it.
Change in Allocation
The change in allocation from the prior reporting period. This is calculated as current allocation - prior allocation.
Change in Allocation (%)
The percent change in allocation from the prior reporting period. This is calculated as (current allocation - prior allocation) / prior allocation.
Cost Basis
The total cost of the shares held. This is calculated as reported shares * avg. share price
Unrealized Gain/Loss
This is the market value of the position as of the effective date minus the cost basis.