Phathom Pharmaceuticals, Inc.
US ˙ NasdaqGS ˙ US71722W1071

SecurityPHAT / Phathom Pharmaceuticals, Inc.
InstitutionCitigroup Inc
Latest Disclosed Ownership29,369 shares
Latest Disclosed Value $ 326,290
Citigroup Inc reports 3.20% increase in ownership of PHAT / Phathom Pharmaceuticals, Inc.

On May 11, 2026 - Citigroup Inc filed a 13F-HR form disclosing ownership of 29,369 shares of Phathom Pharmaceuticals, Inc. (US:PHAT) valued at $326,290 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 13, 2026 disclosing 28,459 shares of Phathom Pharmaceuticals, Inc.. This represents a change in shares of 3.20% during the quarter. The current value of the position is $296,333 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)
2026-05-11 2026-03-31 13F PHATHOM PHARMACEUTICALS COM 71722W107 29,369 910 3.20 326 -30.93 0.0001
2026-02-13 2025-12-31 13F PHATHOM PHARMACEUTICALS COM 71722W107 28,459 14,824 108.72 472 195.00 0.0002
2025-11-10 2025-09-30 13F PHATHOM PHARMACEUTICALS COM 71722W107 13,635 -503,612 -97.36 160 -96.77 0.0001
2025-08-11 2025-06-30 13F PHATHOM PHARMACEUTICALS COM 71722W107 517,247 -13,612 -2.56 4,960 49.04 0.0024
2025-05-12 2025-03-31 13F PHATHOM PHARMACEUTICALS COM 71722W107 530,859 486,282 1,090.88 3,328 821.88 0.0017
2025-02-12 2024-12-31 13F PHATHOM PHARMACEUTICALS COM 71722W107 44,577 13,056 41.42 362 -36.56 0.0002
2024-11-12 2024-09-30 13F PHATHOM PHARMACEUTICALS COM 71722W107 31,521 22,665 255.93 570 525.27 0.0003
2024-08-12 2024-06-30 13F PHATHOM PHARMACEUTICALS COM 71722W107 8,856 2,811 46.50 91 42.19 0.0001
2024-05-10 2024-03-31 13F PHATHOM PHARMACEUTICALS COM 71722W107 6,045 396 7.01 64 25.49 0.0000
2024-02-09 2023-12-31 13F PHATHOM PHARMACEUTICALS COM 71722W107 5,649 1,821 47.57 52 30.77 0.0000
2023-12-06 2023-09-30 13F/A-1 PHATHOM PHARMACEUTICALS COM 71722W107 3,828 -5,256 -57.86 40 -70.00 0.0000
2023-11-09 2023-09-30 13F PHATHOM PHARMACEUTICALS COM 71722W107 3,828 -5,256 40 0.0000
2023-08-10 2023-06-30 13F PHATHOM PHARMACEUTICALS COM 71722W107 9,084 8,138 860.25 130 2,066.67 0.0001
2023-05-11 2023-03-31 13F PHATHOM PHARMACEUTICALS COM 71722W107 946 -186 -16.43 7 -50.00 0.0000
2023-02-09 2022-12-31 13F PHATHOM PHARMACEUTICALS COM 71722W107 1,132 -115 -9.22 13 -14.29 0.0000
2022-11-10 2022-09-30 13F PHATHOM PHARMACEUTICALS COM 71722W107 1,247 -1,262 -50.30 14 -33.33 0.0000
2022-08-10 2022-06-30 13F PHATHOM PHARMACEUTICALS COM 71722W107 2,509 413 19.70 21 -27.59 0.0000
2022-05-12 2022-03-31 13F PHATHOM PHARMACEUTICALS COM 71722W107 2,096 -5,355 -71.87 29 -80.27 0.0000
2022-02-10 2021-12-31 13F PHATHOM PHARMACEUTICALS COM 71722W107 7,451 1,971 35.97 147 -16.48 0.0001
2021-11-10 2021-09-30 13F PHATHOM PHARMACEUTICALS COM 71722W107 5,480 2,640 92.96 176 83.33 0.0001
2021-08-10 2021-06-30 13F PHATHOM PHARMACEUTICALS COM 71722W107 2,840 993 53.76 96 39.13 0.0001
2021-05-13 2021-03-31 13F PHATHOM PHARMACEUTICALS COM 71722W107 1,847 -1,447 -43.93 69 -37.27 0.0000
2021-02-11 2020-12-31 13F PHATHOM PHARMACEUTICALS COM 71722W107 3,294 2,176 194.63 110 168.29 0.0001
2020-11-12 2020-09-30 13F PHATHOM PHARMACEUTICALS COM 71722W107 1,118 -2,144 -65.73 41 -61.68 0.0000
2020-08-12 2020-06-30 13F PHATHOM PHARMACEUTICALS COM 71722W107 3,262 21 0.65 107 28.92 0.0001
2020-05-12 2020-03-31 13F PHATHOM PHARMACEUTICALS COM 71722W107 3,241 1,083 50.19 83 23.88 0.0001
2020-02-12 2019-12-31 13F PHATHOM PHARMACEUTICALS COM 71722W107 2,158 2,158 67 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.