Antero Midstream Corporation
US ˙ NYSE ˙ US03676B1026

SecurityAM / Antero Midstream Corporation
InstitutionSei Investments Co
Latest Disclosed Ownership104,322 shares
Latest Disclosed Value $ 1,855,751
Sei Investments Co ownership in AM / Antero Midstream Corporation

On February 13, 2026 - Sei Investments Co filed a 13F-HR form disclosing ownership of 104,322 shares of Antero Midstream Corporation (US:AM) valued at $1,855,888 USD as of December 31, 2025. The entity filed a previous 13F-HR on November 13, 2025 disclosing 125,402 shares of Antero Midstream Corporation. This represents a change in shares of -16.81% during the quarter. The current value of the position is $2,218,929 USD.

Sei Investments Co has a history of taking positions in derivatives of the underlying security (AM) in the form of stock options.

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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Institutional Put/Call Ratios
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In addition to reporting standard equity and debt issues, institutions with more than 100MM assets under management must also disclose their put and call option holdings. Since put options generally indicate negative sentiment, and call options indicate positive sentiment, we can get a sense of the overall institutional sentiment by plotting the ratio of puts to calls. The chart to the right plots the historical put/call ratio for this instrument.

Using Put/Call Ratio as an indicator of investor sentiment overcomes one of the key deficiencies of using total institutional ownership, which is that a significant amount of assets under management are invested passively to track indices. Passively-managed funds do not typically buy options, so the put/call ratio indicator more closely tracks the sentiment of actively-managed funds.

AM / Antero Midstream Corporation Historical Put/Call Ratio
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)
2026-02-13 2025-12-31 13F ANTERO MIDSTREAM COM 03676B102 104,322 -21,080 -16.81 1,856 -23.88 0.0018
2025-11-13 2025-09-30 13F ANTERO MIDSTREAM COM 03676B102 125,402 20,444 19.48 2,438 22.59 0.0026
2025-08-14 2025-06-30 13F ANTERO MIDSTREAM COM 03676B102 104,958 40,910 63.87 1,989 72.57 0.0023
2025-05-14 2025-03-31 13F/A-1 ANTERO MIDSTREAM COM 03676B102 64,048 29,990 88.06 1,153 124.56 0.0015
2025-05-13 2025-03-31 13F ANTERO MIDSTREAM COM 03676B102 42,230 8,172 699 0.0008
2025-02-11 2024-12-31 13F ANTERO MIDSTREAM COM 03676B102 34,058 -24,179 -41.52 514 -41.44 0.0007
2024-11-12 2024-09-30 13F ANTERO MIDSTREAM COM 03676B102 58,237 -16,400 -21.97 876 -20.36 0.0011
2024-08-13 2024-06-30 13F ANTERO MIDSTREAM COM 03676B102 74,637 54,892 278.00 1,100 297.11 0.0016
2024-05-07 2024-03-31 13F ANTERO MIDSTREAM COM 03676B102 19,745 4,273 27.62 278 43.52 0.0004
2024-02-14 2023-12-31 13F ANTERO MIDSTREAM COM 03676B102 15,472 -50,486 -76.54 194 -75.57 0.0003
2023-11-14 2023-09-30 13F ANTERO MIDSTREAM COM 03676B102 65,958 51,856 367.72 790 384.66 0.0014
2023-08-11 2023-06-30 13F ANTERO MIDSTREAM COM 03676B102 14,102 359 2.61 164 13.19 0.0003
2023-05-12 2023-03-31 13F ANTERO MIDSTREAM COM 03676B102 13,743 13,743 144 0.0003
2022-05-13 2022-03-31 13F ANTERO MIDSTREAM COM 03676B102 0 -37,430 -100.00 0 -100.00
2022-02-14 2021-12-31 13F ANTERO MIDSTREAM COM 03676B102 37,430 408 1.10 396 -4.12 0.0007
2021-11-12 2021-09-30 13F ANTERO MIDSTREAM COM 03676B102 37,022 757 2.09 413 2.48 0.0009
2021-08-06 2021-06-30 13F ANTERO MIDSTREAM COM 03676B102 36,265 -13,733 -27.47 403 6.33 0.0009
2021-05-12 2021-03-31 13F ANTERO MIDSTREAM COM 03676B102 49,998 0 0.00 379 0.00 0.0010
2021-02-08 2020-12-31 13F ANTERO MIDSTREAM COM 03676B102 49,998 -48,098 -49.03 379 -6.19 0.0010
2020-12-04 2020-09-30 13F/A-1 ANTERO MIDSTREAM COM 03676B102 98,096 98,096 404 0.0012
2020-11-06 2020-09-30 13F ANTERO MIDSTREAM COM 03676B102 100,790 100,790 418 1,006.4511
2020-02-06 2019-12-31 13F ANTERO MIDSTREAM COM 03676B102 0 -110,905 -100.00 0 -100.00
2019-11-12 2019-09-30 13F ANTERO MIDSTREAM COM 03676B102 110,905 -1,932 -1.71 821 -36.50 0.0021
2019-08-14 2019-06-30 13F ANTERO MIDSTREAM COM 03676B102 112,837 -313,361 -73.52 1,293 -77.98 0.0042
2019-05-15 2019-03-31 13F ANTERO MIDSTREAM COM 03676B102 426,198 191,558 81.64 5,873 47.93 0.0197
2019-02-13 2018-12-31 13F ANTERO MIDSTREAM GP COM SHS REPSTG 03675Y103 234,640 0 0.00 3,970 0.00 0.0141
2018-11-08 2018-09-30 13F ANTERO MIDSTREAM GP COM SHS REPSTG 03675Y103 234,640 -5,547 -2.31 3,970 -12.36 0.0144
2018-08-03 2018-06-30 13F ANTERO MIDSTREAM GP COM SHS REPSTG 03675Y103 240,187 41,577 20.93 4,530 42.63 0.0154
2018-05-11 2018-03-31 13F ANTERO MIDSTREAM GP COM SHS REPSTG 03675Y103 198,610 1,185 0.60 3,176 -18.42 0.0122
2018-05-11 2018-03-31 13F ANTERO MIDSTREAM PARTNERS UNT LTD PARTN 03673L103 686 -196,739 18 0.0001
2018-02-08 2017-12-31 13F ANTERO MIDSTREAM GP COM SHS REPSTG 03675Y103 197,425 24,824 14.38 3,893 10.19 0.0135
2017-11-06 2017-09-30 13F ANTERO MIDSTREAM GP COM SHS REPSTG 03675Y103 172,601 97,148 128.75 3,533 113.09 0.0126
2017-07-31 2017-06-30 13F ANTERO MIDSTREAM GP COM SHS REPSTG 03675Y103 75,453 75,453 1,658 0.0066
2015-08-07 2015-06-30 13F/A-1 ANTARES PHARMA PUT 03673L103 0 -795 -100.00 0 -100.00
2015-08-04 2015-06-30 13F ANTERO MIDSTREAM PARTNERS UNT LTD PARTN 03673L103 0 -795 0
2015-05-14 2015-03-31 13F/A-1 ANTERO MIDSTREAM PARTNERS UNT LTD PARTN 03673L103 795 -3,246 -80.33 19 -82.88 0.0002
2015-05-01 2015-03-31 13F ANTARES PHARMA PUT 03673L103 795 795 19 0.0002
2015-02-10 2014-12-31 13F ANTERO MIDSTREAM PARTNERS UNT LTD PARTN 03673L103 4,041 4,041 111 0.0010
Disclosed Put Options
File
Date
Effective
Date
Form Security Class ID Opt Avg Share Price Shares ΔShares
(%)
Value
(x1000)
ΔValue
(%)
Prior Allocation
(%)
Allocation
(%)
ΔAllocation
(%)
Cost Basis
(x1000)
Profit
(x1000)
Return
(%)
2015-08-07 2015-06-30 13F/A ANTARES PHARMA PUT 0 -100.00 0 -100.00 n/a n/a n/a
2015-05-01 2015-03-31 13F ANTARES PHARMA PUT 795 19 n/a n/a n/a
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.