Black Stone Minerals (NYSE: BSM) director adds 37,650 common units

Rhea-AI Filing Summary

Black Stone Minerals, L.P. director D. Mark DeWalch reported an open-market purchase of 37,650 common units representing limited partner interests on May 28, 2026 at a weighted average price of $13.2096 per unit. After this transaction, he directly holds 431,495 common units.

The filing also shows indirect holdings, including 6,749 common units held by his wife, 40,809 common units held by the Donald Mark DeWalch Trust, and 558,522 common units held by DeWalch Diversified LP. The price reflects multiple trades between $13.19 and $13.205 per unit.

Insider Trade Summary

Net Buyer: 37,650 shares ($497,341)

Net Buy 4 txns

Insider DeWalch D Mark

Role null

Bought 37,650 shs ($497K)

Type	Security	Shares	Price	Value
Purchase	Common units representing limited partner interests	37,650	$13.2096	$497K
holding	Common units representing limited partner interests	--	--	--
holding	Common units representing limited partner interests	--	--	--
holding	Common units representing limited partner interests	--	--	--

Holdings After Transaction: Common units representing limited partner interests — 431,495 shares (Direct, null); Common units representing limited partner interests — 558,522 shares (Indirect, By DeWalch Diversified LP)

Footnotes (1)

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Key Figures

Units purchased: 37,650 units Weighted average price: $13.2096 per unit Price range: $13.19–$13.205 per unit +4 more

7 metrics

Units purchased 37,650 units Open-market purchase on May 28, 2026

Weighted average price $13.2096 per unit Price for 37,650 units purchased

Price range $13.19–$13.205 per unit Range of individual trade prices on May 28, 2026

Direct holdings after transaction 431,495 units Common units directly owned following purchase

Indirect holdings by wife 6,749 units Common units held indirectly through spouse

Indirect holdings by trust 40,809 units Common units held by Donald Mark DeWalch Trust

Indirect holdings by LP 558,522 units Common units held by DeWalch Diversified LP

Key Terms

open-market purchase, weighted average price, indirect ownership, common units representing limited partner interests

4 terms

open-market purchase financial

"Purchase in open market or private transaction"

An open-market purchase is when an investor or a company buys shares on a public stock exchange at the going market price, rather than through a private deal. It matters to investors because these purchases change how many shares are available, can push the stock price up or signal confidence from large buyers, and often affect per-share metrics like earnings—think of it like someone buying lots of apples off a grocery shelf, reducing supply and potentially raising the price.

weighted average price financial

"The price reported in Column 4 is a weighted average price."

Weighted average price is the average price of a security where each trade or component is counted according to its size, so bigger trades pull the average more than smaller ones. Think of it like calculating the average cost of a grocery haul where items you bought more of have greater influence on the final per-item cost. Investors use it to understand the true average price paid or received, judge execution quality, and compare trading performance against market movement.

indirect ownership financial

"direct_or_indirect": "I", "nature_of_ownership": "By wife""

common units representing limited partner interests financial

"security_title": "Common units representing limited partner interests""

Form 4 Insider Transactions: What Each Field Means →

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

DeWalch D Mark

(Last) (First) (Middle)

1001 FANNIN STREET, SUITE 2020

(Street)

HOUSTON TEXAS 77002

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
Black Stone Minerals, L.P. [ BSM ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director		10% Owner
	Officer (give title below)		Other (specify below)

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
05/28/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common units representing limited partner interests	05/28/2026		P		37,650	A	$13.2096(1)	431,495	D
Common units representing limited partner interests								558,522	I	By DeWalch Diversified LP
Common units representing limited partner interests								40,809	I	By Donald Mark DeWalch Trust
Common units representing limited partner interests								6,749	I	By wife

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. The price reported in Column 4 is a weighted average price. These common units were purchased in multiple transactions at prices ranging from $13.19 to $13.205, inclusive. The reporting person undertakes to provide to the issuer, any security holder of the issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of common units purchased at each separate price within the ranges set forth in this footnote.

Remarks:

	/s/ Steve Putman, attorney-in-fact for D. Mark DeWalch	05/28/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 4: SEC 1474 (03-26)

FAQ

What insider transaction did BSM director D. Mark DeWalch report?

Director D. Mark DeWalch reported buying 37,650 Black Stone Minerals common units in the open market. The units were purchased on May 28, 2026 at a weighted average price of $13.2096 per unit, based on multiple trades within a narrow price range.

At what price did the BSM units trade in DeWalch’s latest Form 4?

The reported weighted average purchase price was $13.2096 per Black Stone Minerals common unit. A footnote explains that the units were bought in multiple transactions, with individual trade prices ranging from $13.19 to $13.205 per unit, inclusive, on the transaction date.

How many BSM units does DeWalch hold directly after this transaction?

After the May 28, 2026 purchase, DeWalch directly holds 431,495 common units of Black Stone Minerals. This updated direct ownership figure reflects the addition of 37,650 units acquired in the open-market transaction reported in the Form 4 filing with the Securities and Exchange Commission.

What indirect BSM holdings related to DeWalch are disclosed in the Form 4?

The filing discloses several indirect holdings associated with DeWalch. These include 6,749 common units held by his wife, 40,809 common units held by the Donald Mark DeWalch Trust, and 558,522 common units held by DeWalch Diversified LP, all reported as indirect ownership positions.

How many BSM units did DeWalch buy versus sell in this Form 4?

This Form 4 shows a net purchase only, with 37,650 Black Stone Minerals common units bought and no reported sales. The transaction summary categorizes the activity as one open-market purchase, resulting in a net-buy direction and increasing DeWalch’s overall holdings of the partnership’s common units.