[Form 4] Black Stone Minerals, L.P. Insider Trading Activity

Rhea-AI Filing Summary

Black Stone Minerals, L.P. director Ashley J. Longmaid reported an open-market sale of 11,128 common units representing limited partner interests at a weighted average price of $13.4523 per unit. Following the sale, Longmaid directly holds 137,335 common units. The sale was executed through multiple trades between $13.41 and $13.48.

Insider Trade Summary

Net Seller: 11,128 shares ($149,697)

Net Sell 1 txn

Insider Longmaid Ashley J

Role null

Sold 11,128 shs ($150K)

Type	Security	Shares	Price	Value
Sale	Common units representing limited partner interests	11,128	$13.4523	$150K

Holdings After Transaction: Common units representing limited partner interests — 137,335 shares (Direct, null)

Footnotes (1)

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Key Figures

Units sold: 11,128 units Weighted average sale price: $13.4523 per unit Post-sale holdings: 137,335 units +2 more

5 metrics

Units sold 11,128 units Open-market sale on 2026-05-12

Weighted average sale price $13.4523 per unit Price for 11,128 units sold

Post-sale holdings 137,335 units Common units directly held after transaction

Sale price range $13.41–$13.48 Range of prices for multiple sale transactions

Net shares sold 11,128 units Net-sell direction per transaction summary

Key Terms

Common units representing limited partner interests, open-market sale, weighted average price, Form 4

4 terms

Common units representing limited partner interests financial

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

open-market sale financial

"transaction_action: "open-market sale" for 11,128 common units"

An open-market sale is when a shareholder sells existing shares directly on a public exchange to any willing buyer, rather than through a private deal. Think of it like putting goods on a busy market stall where price is set by supply and demand; for investors it matters because such sales increase available supply, can put short-term downward pressure on the stock price, and signal changes in liquidity or investor confidence.

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.

Form 4 regulatory

"INSIDER FILING DATA (Form 4): transaction by a reporting person"

Form 4 is a official document that company insiders, such as executives or major shareholders, file with regulators whenever they buy or sell company shares. It provides transparency about how those with inside knowledge are trading, helping investors see if insiders are confident in the company's prospects or may be selling for personal reasons. This information can influence investor decisions by revealing insiders' perspectives on the company's value.

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^*

Longmaid Ashley J

(Last) (First) (Middle)

1001 FANNIN ST., 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)
05/12/2026

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	05/12/2026		S		11,128	D	$13.4523(1)	137,335	D

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 sold in multiple transactions at prices ranging from $13.41 to 13.48, 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 sold at each separate price within the ranges set forth in this footnote.

Remarks:

	/s/ Steve Putman, attorney-in-fact for Ashley J. Longmaid	05/13/2026
	** 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 did Black Stone Minerals (BSM) director Ashley J. Longmaid report in this Form 4?

Ashley J. Longmaid reported an open-market sale of 11,128 common units of Black Stone Minerals. The transactions occurred at a weighted average price of $13.4523 per unit, reflecting routine portfolio activity while maintaining a substantial remaining direct ownership position.

How many Black Stone Minerals (BSM) units did the director sell and at what price?

The director sold 11,128 common units representing limited partner interests. The weighted average sale price was $13.4523 per unit, with individual trades executed at prices ranging from $13.41 to $13.48, according to the Form 4’s transaction and footnote disclosure.

How many Black Stone Minerals (BSM) units does the director hold after the reported sale?

After the reported sale, the director holds 137,335 common units directly. This post-transaction holding, disclosed in the Form 4, shows that the sale affected only a portion of the director’s overall position, leaving a sizeable continuing ownership stake in Black Stone Minerals.

Was the Black Stone Minerals (BSM) director’s transaction an open-market sale?

Yes. The Form 4 describes the transaction as an open-market sale of common units. The sale involved multiple trades within a price range of $13.41 to $13.48, with a calculated weighted average price of $13.4523 per unit for the reported 11,128 units sold.

What price range is disclosed for the Black Stone Minerals (BSM) units sold by the director?

The Form 4 footnote states the common units were sold in multiple transactions at prices ranging from $13.41 to $13.48, inclusive. The reported figure of $13.4523 per unit represents the weighted average sale price for all 11,128 units sold in this transaction.