[Form 4] Mayville Engineering Company, Inc. Insider Trading Activity

Rhea-AI Filing Summary

Sean P. Leuba, Senior Vice President, Corporate Development & General Counsel of Mayville Engineering Company (MEC), reported changes in his beneficial ownership. The filing shows a purchase of 500 common shares at $13.56 and a disposition of 18,539 common shares. Following the reported activity, indirect holdings include 2,500 shares via an ESOP/401(k) plan. In addition, Leuba holds equity compensation: 14,526 and 13,938 restricted stock units (with staggered vesting schedules) and a stock option covering 21,552 shares with an exercise price of $16.22. The disclosure lists explicit vesting schedules for the RSUs and vesting terms for the option.

Positive

• Purchased 500 common shares at $13.56, indicating a direct purchase by the reporting officer
• Holds substantial equity compensation: 14,526 RSUs, 13,938 RSUs, and a stock option for 21,552 shares (exercise price $16.22), aligning long‑term interests with shareholders
• Indirect ESOP/401(k) holdings reported (2,500 shares), reflecting participation in company retirement plans

Negative

• Disposition of 18,539 common shares reported, a materially large sale in absolute terms
• Option exercise price ($16.22) is specified and may be above or below market at different times (market context not provided in filing)

Insights

Securities Analyst

TL;DR: Insider sold a large block while retaining significant equity awards; mixed signal for investors.

The Form 4 shows both a meaningful disposition (18,539 shares sold) and a small purchase (500 shares at $13.56), alongside substantial equity compensation: two RSU grants totaling 28,464 underlying shares and a stock option for 21,552 shares at $16.22. From a trading-impact perspective, the large sale is material in absolute terms and could affect near-term float if shares were sold into the market, while the retained and unvested awards indicate continued alignment with shareholder value. The filing provides clear vesting schedules, which helps assess timing of future potential sales.

Corporate Governance Expert

TL;DR: Transaction mix looks consistent with compensation vesting and personal trading; no explicit governance red flags in the filing.

The report documents structured equity holdings (two RSU tranches and an option grant) with specified vesting dates and an ESOP/401(k) indirect holding. The presence of scheduled vesting dates for RSUs and stated vesting for options suggests much of the insider's equity exposure arises from compensation plans rather than opportunistic trading. The large disposition is notable but the filing does not include contextual details (e.g., planned sales program), so governance implications are neutral based solely on the disclosed information.

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)
	SVP, Corp. Development & GC

3. Date of Earliest Transaction (Month/Day/Year)
08/11/2025

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	08/11/2025		P		500	A	$13.56	2,500(1)	I	by ESOP and/or 401(k) Plan
Common Stock								18,539	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/ Russell E. Ryba, Attorney-in-Fact for Sean P. Leuba	08/11/2025
	** 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.

FAQ

What transactions did Sean P. Leuba report on the MEC Form 4?

The Form 4 reports a purchase of 500 common shares at $13.56 and a disposition of 18,539 common shares by Sean P. Leuba.

How many restricted stock units and options does Sean P. Leuba hold according to the filing?

The filing shows 14,526 RSUs in one tranche, 13,938 RSUs in another, and a stock option covering 21,552 shares with an exercise price of $16.22.

Are there vesting schedules disclosed for the RSUs and options?

Yes. The RSUs have staggered vesting schedules (each tranche vests one‑third on stated March dates) and the option vesting is disclosed as 50% on two specified February dates.

Does the filing show any indirect ownership?

Yes. The report indicates 2,500 shares are held indirectly via an ESOP and/or 401(k) plan.

Does the Form 4 indicate whether the large share disposition was part of a planned trading program?

No. The filing discloses the sale amount (18,539 shares) but does not state whether it was executed under a 10b5-1 plan or other prearranged program.