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Yorktown Energy Partners X, L.P.

CIK 1577919 · last filed 2024-12-18

Yorktown Energy Partners X, L.P. is a corporate insider who has filed 18 SEC Form 4 insider transactions across 5 companies since 2016. The most recent filing, for SEI, was dated May 8, 2026. Across all open-market trades the lifetime net is −$150.4M, making them a net seller over the disclosed history. Current disclosed insider exposure totals $58.7M across reported positions. The firm reports its address in New York, NY. 9 SEC filings were submitted jointly with Riley Exploration Group, LLC.

"Disclosed insider exposure" sums this person's most-recently-reported share counts across each company they're an insider in, multiplied by the current underlying price. It is not net worth — it misses retail holdings, private investments, real estate, index funds, and any company where the person isn't an SEC-reporting insider. For informational purposes only.

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Disclosed Exposure

$58.71M

Companies

5

Total Filings

18

Lifetime Open-Market Net

-$150.37M

Filer Profile

Reported Address
410 PARK AVENUE
20TH FLOOR
NEW YORK, NY 10022
Phone
(212) 515-2115
State of Incorporation
DE
Related Filers
Riley Exploration Group, LLC — 9 joint filings, latest 2024-04-10
Yorktown Energy Partners IX, L.P. — 9 joint filings, latest 2024-04-10
Yorktown IX Associates LLC — 9 joint filings, latest 2024-04-10
Yorktown X Associates LLC — 9 joint filings, latest 2024-04-10
Yorktown VIII Associates LLC — 3 joint filings, latest 2021-10-15
Profile details as reported on the filer's SEC submissions — for individual insiders the address is often in care of the issuer. Related filers are identified from jointly filed SEC submissions and shared reported addresses. View filings on SEC EDGAR.

Holdings By Company

Latest on-record share count from this person's most recent non-derivative Form 4 transaction in each company. Disclosed exposure = shares × current underlying price.
Symbol Role Shares Price Disclosed Exposure Lifetime OM Net Filings Latest Filed
Solaris Energy Infrastructure, Inc. (SOI) Delisted 10%+ Owner 975,000 $11.32 $11.04M -$135.66M 6 2024-12-18
REPX 10%+ Owner 390,860 $43.51 $17.01M $0 2 2023-07-18
Brigham Minerals, Inc. (MNRL) Delisted 10%+ Owner 2,683,371 $32.50 $87.21M -$13.94M 1 2019-12-18
METC 10%+ Owner 3,726,959 $11.19 $41.70M -$766.9K 1 2017-02-10
Extraction Oil & Gas, Inc. (XOG) Delisted 10%+ Owner 17,554,262 $68.54 $1.20B $0 1 2016-10-31

Recent Filings

18 filings
Insider activity across all companies, newest first. Form 4 rows are post-trade confirmations (buys, sells, grants, exercises). Notice (144) rows are pre-trade notices of intent to sell restricted or control stock under Rule 144 — they may not all execute. Compare adjacent dates to see which notices became actual sales.
Filed Symbol Action Net Shares Net $ Link
2026-05-08 SEI Notice (144) −2,000,000 -$149.00M EDGAR
2026-03-24 METC Notice (144) −49,928 -$573.7K EDGAR
2026-03-05 METC Notice (144) −533,284 -$8.45M EDGAR
2025-03-20 METC Notice (144) −266,642 -$2.48M EDGAR
2025-03-20 METC Notice (144) −49,604 -$425.1K EDGAR
2024-12-18 Solaris Energy Infrastructure, Inc. (SOI) Delisted Mixed −975,000 -$23.41M EDGAR
2023-11-13 METC Notice (144) −25,383 -$412.5K EDGAR
2023-11-13 METC Notice (144) −496,682 -$9.09M EDGAR
2023-07-18 REPX Other (J) −5,376,270 $0 EDGAR
2021-07-30 REPX Mixed — $0 EDGAR
Showing 1–10 of 18
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Form 4 codes: P = open-market purchase · S = open-market sale · A = grant/award · M = option exercise · F = tax withholding at vest · G = bona-fide gift · D = disposition to issuer · J = other (see filing footnote). Only P / S codes carry directional signal.
Notice (144 / 144/A): Form 144 is a notice of intent to sell restricted/control stock under Rule 144, filed before the sale; 144/A is an amendment. Many notices are pre-scheduled under Rule 10b5-1 plans. A Form 4 with code S typically follows within a few days when the planned sale executes; missing follow-up Form 4s suggest the notice was cancelled or modified.