MEC GC Sean Leuba sells 9,198 company shares

Mayville Engineering Company, Inc. insider Sean P. Leuba, the company’s GC & Secretary, reported open-market sales of company stock on March 5, 2026.

Rhea-AI Filing Summary

Mayville Engineering Company, Inc. insider Sean P. Leuba, the company’s GC & Secretary, reported open-market sales of company stock on March 5, 2026. He sold 2,500 shares of common stock indirectly through an ESOP/401(k) at $20.07 per share and 6,698 shares directly at $18.81 per share, for total reported sales of 9,198 shares.

After these transactions, Leuba directly holds 11,841 common shares and maintains equity awards, including 14,526 and 13,938 restricted stock units that vest in annual thirds through March 2027 and March 2028, and 21,552 stock options that vest in two equal installments on February 28, 2024 and 2025.

Insider Trade Summary

Net Seller: 9,198 shares

Net Sell 5 txns

Insider Leuba Sean P

Role GC & Secretary

Sold 9,198 shs ($176K)

Type	Security	Shares	Price	Value
Sale	Common Stock	2,500	$20.07	$50K
Sale	Common Stock	6,698	$18.81	$126K
holding	Restricted Stock Units	--	--	--
holding	Restricted Stock Units	--	--	--
holding	Stock Option (right to buy)	--	--	--

Holdings After Transaction: Common Stock — 0 shares (Indirect, by ESOP and/or 401(k) Plan); Common Stock — 11,841 shares (Direct); Restricted Stock Units — 28,464 contracts (Direct); Stock Option (right to buy) — 21,552 contracts (Direct)

Footnotes (4)

1. F1. Reflects the most recent ESOP and 401(k) balance.
2. F2. The restricted stock units will vest 1/3 on each of March 15, 2025, 2026 and 2027.
3. F3. The restricted stock units will vest 1/3 on each of March 15, 2026, 2027 and 2028.
4. F4. The options will vest 50% on each of February 28, 2024 and February 28, 2025.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What insider transaction did MEC’s Sean P. Leuba report on this Form 4?

Sean P. Leuba reported selling a total of 9,198 MEC common shares on March 5, 2026. This included indirect ESOP/401(k) shares and directly held shares, both sold in open-market transactions at disclosed per-share prices.

How many MEC shares did Sean P. Leuba sell directly and indirectly?

Leuba sold 2,500 MEC common shares indirectly through an ESOP and/or 401(k) plan and 6,698 common shares held directly. Both sales occurred on March 5, 2026 in open-market transactions.

What were the sale prices for Sean P. Leuba’s MEC stock transactions?

The indirect ESOP/401(k) sale of 2,500 MEC shares was at $20.07 per share. The direct sale of 6,698 MEC shares was at $18.81 per share, both described as open-market or private transactions.

How many MEC shares does Sean P. Leuba hold after these sales?

Following the reported transactions, Leuba holds 11,841 MEC common shares directly. The ESOP and/or 401(k) balance related to these indirect shares is shown as 0 shares after the sale, reflecting the most recent plan balance.

What MEC restricted stock units does Sean P. Leuba hold and when do they vest?

Leuba holds 14,526 MEC restricted stock units vesting one-third on March 15, 2025, 2026, and 2027. He also holds 13,938 units vesting one-third on March 15, 2026, 2027, and 2028, as disclosed in the vesting footnotes.

What stock options in MEC does Sean P. Leuba currently hold?

Leuba holds 21,552 MEC stock options labeled as a right to buy common stock. The options vest 50% on February 28, 2024 and the remaining 50% on February 28, 2025, according to the disclosed vesting schedule.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Accepted by SEC EDGAR 03/09/2026 - 04:22 PM Learn about SEC filing dates

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^*

Leuba Sean P

(Last) (First) (Middle)

135 SOUTH 84TH STREET

SUITE 300

(Street)

MILWAUKEE WI 53214

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Mayville Engineering Company, Inc. [ MEC ]

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

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

3. Date of Earliest Transaction (Month/Day/Year)
03/05/2026

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

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

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

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 Stock	03/05/2026		S		2,500	D	$20.07	0(1)	I	by ESOP and/or 401(k) Plan
Common Stock	03/05/2026		S		6,698	D	$18.81	11,841	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
Restricted Stock Units	$0							(2)	(2)	Common Stock	14,526		14,526	D
Restricted Stock Units	$0							(3)	(3)	Common Stock	13,938		13,938	D
Stock Option (right to buy)	$16.22							(4)	02/28/2033	Common Stock	21,552		21,552	D

Explanation of Responses:

1. Reflects the most recent ESOP and 401(k) balance.

2. The restricted stock units will vest 1/3 on each of March 15, 2025, 2026 and 2027.

3. The restricted stock units will vest 1/3 on each of March 15, 2026, 2027 and 2028.

4. The options will vest 50% on each of February 28, 2024 and February 28, 2025.

	/s/ Garrett F. Bishop, Attorney-in-Fact for Sean P. Leuba	03/09/2026
	** 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.