Tandem Diabetes Care, Inc.
US ˙ NasdaqGM ˙ US8753722037

SecurityTNDM / Tandem Diabetes Care, Inc.
InstitutionAmalgamated Bank
Latest Disclosed Ownership19,518 shares
Latest Disclosed Value $ 374
Amalgamated Bank reports 0.62% decrease in ownership of TNDM / Tandem Diabetes Care, Inc.

On May 8, 2026 - Amalgamated Bank filed a 13F-HR form disclosing ownership of 19,518 shares of Tandem Diabetes Care, Inc. (US:TNDM) valued at $374,160 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 5, 2026 disclosing 19,640 shares of Tandem Diabetes Care, Inc.. The current value of the position is $351,910 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)
2026-05-08 2026-03-31 13F TANDEM DIABETES CARE COM 875372203 19,518 -122 -0.62 0 0.0029
2026-02-05 2025-12-31 13F TANDEM DIABETES CARE COM 875372203 19,640 23 0.12 0 0.0031
2025-10-29 2025-09-30 13F TANDEM DIABETES CARE COM 875372203 19,617 657 3.47 0 0.0017
2025-08-04 2025-06-30 13F TANDEM DIABETES CARE COM 875372203 18,960 184 0.98 0 0.0027
2025-04-25 2025-03-31 13F TANDEM DIABETES CARE COM 875372203 18,776 -448 -2.33 0 0.0031
2025-02-04 2024-12-31 13F TANDEM DIABETES CARE COM 875372203 19,224 -68 -0.35 1 0.0057
2024-10-30 2024-09-30 13F TANDEM DIABETES CARE COM 875372203 19,292 -457 -2.31 1 0.0067
2024-08-12 2024-06-30 13F TANDEM DIABETES CARE COM 875372203 19,749 -2,120 -9.69 1 0.0068
2024-04-23 2024-03-31 13F TANDEM DIABETES CARE COM 875372203 21,869 -5,898 -21.24 1 0.0066
2024-02-06 2023-12-31 13F TANDEM DIABETES CARE COM 875372203 27,767 -1,427 -4.89 1 0.0066
2023-11-08 2023-09-30 13F TANDEM DIABETES CARE COM 875372203 29,194 -709 -2.37 1 0.0052
2023-08-11 2023-06-30 13F TANDEM DIABETES CARE COM 875372203 29,903 -3,811 -11.30 1 -100.00 0.0059
2023-05-02 2023-03-31 13F TANDEM DIABETES CARE COM 875372203 33,714 -15,630 -31.68 1 -50.00 0.0117
2023-02-10 2022-12-31 13F TANDEM DIABETES CARE COM 875372203 49,344 819 1.69 2 -99.91 0.0198
2022-11-09 2022-09-30 13F TANDEM DIABETES CARE COM 875372203 48,525 1,137 2.40 2,322 -17.22 0.0224
2022-08-15 2022-06-30 13F TANDEM DIABETES CARE COM 875372203 47,388 523 1.12 2,805 -48.53 0.0261
2022-08-25 2022-03-31 13F/A-1 TANDEM DIABETES CARE COM 875372203 46,865 -142 -0.30 5,450 -22.97 0.0423
2022-06-30 2022-03-31 13F TANDEM DIABETES CARE COM 875372203 46,865 -142 5,450 0.0433
2022-02-15 2021-12-31 13F/A-1 TANDEM DIABETES CARE COM 875372203 47,007 2,437 5.47 7,075 32.96 0.0522
2022-02-15 2021-12-31 13F TANDEM DIABETES CARE COM 875372203 47,007 2,437 7,075 0.0522
2021-10-29 2021-09-30 13F TANDEM DIABETES CARE COM 875372203 44,570 32,848 280.23 5,321 365.94 0.0449
2021-08-16 2021-06-30 13F TANDEM DIABETES CARE COM 875372203 11,722 874 8.06 1,142 19.33 0.0092
2021-05-13 2021-03-31 13F TANDEM DIABETES CARE COM 875372203 10,848 -873 -7.45 957 -14.63 0.0359
2021-02-12 2020-12-31 13F TANDEM DIABETES CARE COM 875372203 11,721 235 2.05 1,121 -14.03 0.0425
2020-10-30 2020-09-30 13F TANDEM DIABETES CARE COM 875372203 11,486 -123 -1.06 1,304 13.59 0.0567
2020-08-10 2020-06-30 13F TANDEM DIABETES CARE COM 875372203 11,609 1,351 13.17 1,148 73.94 0.0531
2020-05-13 2020-03-31 13F TANDEM DIABETES CARE COM 875372203 10,258 -692 -6.32 660 1.07 0.0161
2020-02-13 2019-12-31 13F TANDEM DIABETES CARE COM 875372203 10,950 1,100 11.17 653 12.39 0.0120
2019-11-13 2019-09-30 13F TANDEM DIABETES CARE COM 875372203 9,850 -123 -1.23 581 -9.64 0.0122
2019-08-14 2019-06-30 13F TANDEM DIABETES CARE COM 875372203 9,973 2,249 29.12 643 31.22 0.0150
2019-05-15 2019-03-31 13F TANDEM DIABETES CARE COM 875372203 7,724 246 3.29 490 72.54 0.0119
2019-02-15 2018-12-31 13F TANDEM DIABETES CARE COM 875372203 7,478 7,478 284 0.0080
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.