Amphastar Pharmaceuticals, Inc.
US ˙ NasdaqGS ˙ US03209R1032

SecurityAMPH / Amphastar Pharmaceuticals, Inc.
InstitutionCitigroup Inc
Latest Disclosed Ownership35,904 shares
Latest Disclosed Value $ 703,359
Citigroup Inc reports 26.96% increase in ownership of AMPH / Amphastar Pharmaceuticals, Inc.

On May 11, 2026 - Citigroup Inc filed a 13F-HR form disclosing ownership of 35,904 shares of Amphastar Pharmaceuticals, Inc. (US:AMPH) valued at $703,359 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 13, 2026 disclosing 28,280 shares of Amphastar Pharmaceuticals, Inc.. This represents a change in shares of 26.96% during the quarter. The current value of the position is $650,580 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.

Upgrade to unlock premium data and export to Excel .

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)
2026-05-11 2026-03-31 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 35,904 7,624 26.96 703 -7.13 0.0002
2026-02-13 2025-12-31 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 28,280 8,465 42.72 757 43.37 0.0003
2025-11-10 2025-09-30 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 19,815 -22,405 -53.07 528 -45.51 0.0002
2025-08-11 2025-06-30 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 42,220 -35,517 -45.69 969 -56.99 0.0005
2025-05-12 2025-03-31 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 77,737 14,566 23.06 2,254 -3.92 0.0012
2025-02-12 2024-12-31 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 63,171 5,359 9.27 2,346 -16.40 0.0014
2024-11-12 2024-09-30 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 57,812 22,817 65.20 2,806 100.50 0.0016
2024-08-12 2024-06-30 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 34,995 47 0.13 1,400 -8.80 0.0009
2024-05-10 2024-03-31 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 34,948 4,008 12.95 1,535 -19.81 0.0010
2024-02-09 2023-12-31 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 30,940 -10,650 -25.61 1,914 0.05 0.0013
2023-12-06 2023-09-30 13F/A-1 AMPHASTAR PHARMACEUTICALS IN COM 03209R103 41,590 3,841 10.18 1,913 -11.85 0.0014
2023-11-09 2023-09-30 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 41,590 3,841 1,913 0.0006
2023-08-10 2023-06-30 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 37,749 13,000 52.53 2,169 133.73 0.0014
2023-05-11 2023-03-31 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 24,749 -6,998 -22.04 928 4.39 0.0007
2023-02-09 2022-12-31 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 31,747 757 2.44 890 2.07 0.0007
2022-11-10 2022-09-30 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 30,990 -349 -1.11 871 -20.09 0.0006
2022-08-10 2022-06-30 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 31,339 -7,325 -18.95 1,090 -21.47 0.0008
2022-05-12 2022-03-31 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 38,664 8,224 27.02 1,388 95.77 0.0008
2022-02-10 2021-12-31 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 30,440 -69 -0.23 709 22.24 0.0004
2021-11-10 2021-09-30 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 30,509 5,307 21.06 580 14.17 0.0003
2021-08-10 2021-06-30 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 25,202 12,515 98.64 508 118.03 0.0003
2021-05-13 2021-03-31 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 12,687 -1,839 -12.66 233 -20.21 0.0002
2021-02-11 2020-12-31 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 14,526 7,197 98.20 292 111.59 0.0002
2020-11-12 2020-09-30 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 7,329 -14,389 -66.25 138 -71.72 0.0001
2020-08-12 2020-06-30 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 21,718 6,023 38.38 488 109.44 0.0004
2020-05-12 2020-03-31 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 15,695 -4,304 -21.52 233 -39.64 0.0002
2020-02-12 2019-12-31 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 19,999 -9,186 -31.48 386 -33.33 0.0003
2019-11-08 2019-09-30 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 29,185 11,260 62.82 579 53.17 0.0005
2019-08-12 2019-06-30 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 17,925 -15,058 -45.65 378 -43.92 0.0003
2019-05-13 2019-03-31 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 32,983 15,440 88.01 674 93.12 0.0006
2019-02-12 2018-12-31 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 17,543 -19,584 -52.75 349 -51.19 0.0004
2018-11-13 2018-09-30 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 37,127 -39,320 -51.43 715 -38.73 0.0006
2018-08-10 2018-06-30 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 76,447 -27,472 -26.44 1,167 -40.12 0.0011
2018-05-11 2018-03-31 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 103,919 -31,553 -23.29 1,949 -25.21 0.0016
2018-02-12 2017-12-31 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 135,472 -53,438 -28.29 2,606 -22.81 0.0021
2017-11-13 2017-09-30 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 188,910 -32,819 -14.80 3,376 -14.75 0.0028
2017-08-11 2017-06-30 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 221,729 165,613 295.13 3,960 387.08 0.0036
2017-05-12 2017-03-31 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 56,116 -17,087 -23.34 813 -39.69 0.0007
2017-02-10 2016-12-31 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 73,203 38,031 108.13 1,348 102.10 0.0012
2016-11-10 2016-09-30 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 35,172 22,083 168.71 667 216.11 0.0006
2016-08-12 2016-06-30 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 13,089 -17,923 -57.79 211 -43.28 0.0002
2016-05-13 2016-03-31 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 31,012 12,934 71.55 372 44.75 0.0004
2016-02-12 2015-12-31 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 18,078 13,935 336.35 257 435.42 0.0003
2015-11-13 2015-09-30 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 4,143 -88,930 -95.55 48 -97.07 0.0000
2015-08-13 2015-06-30 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 93,073 45,802 96.89 1,637 131.54 0.0015
2015-05-14 2015-03-31 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 47,271 36,333 332.17 707 456.69 0.0007
2015-02-17 2014-12-31 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 10,938 8,906 438.29 127 429.17 0.0001
2014-11-14 2014-09-30 13F AMPHASTAR PHARMACEUTICALS IN COM 03209R103 2,032 2,032 24 0.0000
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.