Omnicom (NYSE: OMC) CAO uses 1,348 shares to cover tax bill

Rhea-AI Filing Summary

OMNICOM GROUP INC. (OMC) reported an insider transaction by Andrew Castellaneta, its SVP and Chief Accounting Officer. On 2026-08-15, 1,348 shares of common stock were disposed of at $87.57 per share to satisfy payment of exercise price or tax liability by delivering or withholding securities. Following this transaction, he directly owns 20,795 shares, which include 4,365 shares acquired under Omnicom's employee stock purchase plan.

Insider Trade Summary

Net Seller: 1,348 shares

Net Sell 1 txn

Insider Castellaneta Andrew

Role SVP, Chief Accounting Officer

Type	Security	Shares	Price	Value
Exercise Price or Tax Liability	Common Stock, par value $0.15 per share F1	1,348	$87.57	$118K

Holdings After Transaction: Common Stock, par value $0.15 per share — 20,795 shares (Direct)

Footnotes (1)

1. F1. Includes 4,365 shares acquired under Omnicom's employee stock purchase plan.

Key Figures

Shares disposed: 1,348 shares Transaction price: $87.57 per share Shares owned after transaction: 20,795 shares +1 more

4 metrics

Shares disposed 1,348 shares Shares delivered or withheld on 2026-08-15 for exercise price or tax liability

Transaction price $87.57 per share Price applied to the 1,348 shares disposed in the code F transaction

Shares owned after transaction 20,795 shares Directly owned Omnicom common stock following the 2026-08-15 transaction

ESPP shares included 4,365 shares Portion of post-transaction holdings acquired under Omnicom's employee stock purchase plan

Key Terms

Payment of exercise price or tax liability, employee stock purchase plan, Common Stock, par value $0.15 per share

3 terms

Payment of exercise price or tax liability financial

"described as payment of exercise price or tax liability by delivering or withholding securities"

employee stock purchase plan financial

"Includes 4,365 shares acquired under Omnicom's employee stock purchase plan"

An employee stock purchase plan is a company program that lets workers buy shares through small payroll deductions, often at a discount to the market price and after a set offering period. Think of it like a workplace savings plan that turns into ownership: it encourages employees to share in the company’s success and can create predictable buying or selling of stock that investors watch because it affects supply, demand and employee incentives.

Common Stock, par value $0.15 per share financial

"security title Common Stock, par value $0.15 per share"

FAQ

What insider transaction did OMC report for Andrew Castellaneta?

Omnicom reported that Andrew Castellaneta disposed of 1,348 shares of common stock at $87.57 per share on 2026-08-15. The transaction was for payment of exercise price or tax liability by delivering or withholding securities.

How many OMC shares does Andrew Castellaneta hold after this transaction?

After the reported transaction, Andrew Castellaneta directly holds 20,795 shares of Omnicom common stock. This total includes 4,365 shares that were acquired under Omnicom's employee stock purchase plan.

Was the OMC insider transaction a market sale or tax/exercise-related?

The Form 4 describes the transaction as payment of exercise price or tax liability by delivering or withholding securities. It is coded as transaction type F, not as an open-market purchase or sale.

What was the price used in Andrew Castellaneta’s OMC share disposition?

The disposition of 1,348 Omnicom shares used a price of $87.57 per share. This price applies to the shares delivered or withheld for payment of the exercise price or tax liability associated with the underlying equity event.

Are any of Andrew Castellaneta’s OMC shares held through an employee stock purchase plan?

Yes. A filing footnote states that his direct holdings include 4,365 shares acquired under Omnicom's employee stock purchase plan, which form part of his total 20,795 directly owned shares.

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

See more from StockTitan in Google Search and AI answers. Adds StockTitan as a preferred source · opens Google

Add on Google Not now

Form 4 Insider Transactions: What Each Field Means →

Available on EDGAR 08/18/2026 - 04:32 PM Accepted by SEC EDGAR 08/18/2026 - 04:30 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^*

Castellaneta Andrew

(Last) (First) (Middle)

C/O OMNICOM GROUP INC.

280 PARK AVENUE

(Street)

NEW YORK NEW YORK 10017

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
OMNICOM GROUP INC. [ OMC ]

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

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	SVP, Chief Accounting Officer

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
08/15/2026

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 Stock, par value $0.15 per share	08/15/2026		F		1,348	D	$87.57	20,795(1)	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. Includes 4,365 shares acquired under Omnicom's employee stock purchase plan.

	/s/ Eric J. Cleary, Attorney in Fact for Andrew Castellaneta	08/18/2026
	** 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)