Philip J. Angelastro
Executive Vice President and Chief Financial Officer at Omnicom Group
Thanks, John. As you just heard, we had a strong quarter and our financial performance positions us well for a solid 2025. Let's begin with a review of our performance in the 4th-quarter, beginning with changes in our revenues on Slide 4. Organic growth in the quarter was strong at 5.2%. The impact on revenue from foreign currency translation decreased reported revenue by 0.6%. If rates stay where they are currently, we estimate the impact of foreign currency translation will reduce revenue by 2% to 2.5% for Q1 2025 and 2% for the full-year 2025.
The net impact of acquisition and disposition revenue on reported revenue was positive 1.8%. At this time, we expect the impact of acquisition and disposition revenue will be flat for both Q1 and the full-year 2025. For the full-year 2024, our organic revenue growth was 5.2%, slightly above our stated goal of achieving the higher-end of our target of between 4% to 5%. As John mentioned, our expected organic revenue growth in 2025 is a range of 3.5% to 4.5% based on current market conditions.
Let's turn to Slide 5 and review the Q4 organic revenue growth trends by discipline that are informing our annual outlook. During the quarter, media and advertising was up 7% and primarily reflected growth across our media business with growth in advertising in the low-single digits. Growth in this discipline was particularly strong in the United States, our largest market. Precision marketing growth of 9% was very strong and benefited from year-end project spend. Overall, this was led by double-digit growth in the US, partially offset by mixed performance in other geographies.
We expect solid growth in 2025. Public relations grew 10%, also led by double-digit growth in the US as a result of US election spend, which is partially offset by softer performance internationally. This brought annual growth to approximately 4%. We estimate that the benefit from election spend was approximately $25 million in Q4 and $50 million for the year. Experiential growth of 5% was solid, coming off good results from the Summer Olympics earlier this year, especially in Q2 and Q3 as well as Q1. We do not expect to see 2024 growth levels in '25, given it is not an Olympic year.
Execution and support was up 2%, reflecting continued good results in-field marketing, offset by declines in our merchandising business. Healthcare revenues were down 4%. We are close to lapping a significant client loss and recent wins should start contributing to improved performance during the second-half of 2025. Branding and retail commerce declined by 12%, resulting from reduced client spending in our branding agencies and lower performance in retail commerce, some of which reflects budget allocation where clients move spend to retail media.
Turning to organic revenue growth by geography on Slide 6. Our largest market, the US had organic growth of 10%, finishing off the year-on a strong note. Although several markets in Europe, the Middle-East and Asia-Pacific delivered strong growth. They were offset by negative performance in other markets within these regions. Our businesses in Latin-America delivered strong growth driven by media and advertising. Slide 7 is our revenue by industry sector for the quarter and year-to-date. Overall, our portfolio remained stable as well as diversified. The only notable shift is a two-point increase in consumer products for both the quarter and the year, driven by the flywheel acquisition.
Now let's turn to Slide 8 for a look at our expenses. In the quarter, salary-related service costs were flat with growth from our acquisition of Flywheel, offset by repositioning actions in the second-quarter and our ongoing efforts to nearshore, offshore and increase productivity. Third-party service costs grew in connection with the growth in our revenue, especially in disciplines that have a higher-level of these costs such as media, experiential and field marketing. Third-party incidental costs, which are out-of-pocket costs billed back to clients at our cost were up slightly.
Occupancy and other costs, which include office rent, other occupancy, technology and general office expenses, increased primarily due to the Flywheel acquisition. SG&A expenses decreased due to general cost management. Included in the fourth quarters of both years are approximately $14.5 million of acquisition-related costs for flywheel in 2023 and the IPG transaction in 2024. Please turn to Slide nine and look at our income statement in more detail. Operating expenses in the fourth quarters of both 2024 and 2023 reflect these acquisition costs related to IPG and flywheel, respectively. Removing them from both years, 4th-quarter non-GAAP adjusted EBITDA grew 6.6% and EBITDA margin was flat year-over-year at 16.7%.
For the full-year 2024, our adjusted EBITDA margin was 15.5% compared to 15.6% in 2023, in-line with our guidance for 2024 by balancing ongoing cost-savings initiatives with continued investments in technology platforms and tools for future growth as well as costs related to the integration of Flagwell. For the full-year 2025, on a standalone Omnicom basis, we expect adjusted EBITDA margin to improve by-10 basis-points as we continue to balance cost-savings initiatives with strategic investment opportunities that we believe will continue to drive strong future revenue and EBITDA growth.
Moving down the income statement, net interest expense in the 4th-quarter of 2024 increased by $11.3 million to $38.1 million. The change was driven by a $12.4 million increase in interest expense due to higher outstanding debt, primarily from the $600 million of Eurobonds we issued in Q1 2024 in connection with the Flagwell acquisition, offset by a $1.1 million increase in interest income due to higher average cash balances. Our income tax-rate of 26.4% in Q4 '24 was flat with the prior year. For the full-year 2025, we expect the rate to be between 26.5% and 27%.
Net income growth of 5.2%, coupled with fewer diluted shares outstanding from our share repurchase activity drove a 6.1% lift in diluted earnings per share. On an adjusted basis, excluding after-tax amortization, Q4 2024 diluted earnings per share was up 6.6% to $2.41. Note that the negative impact of foreign-exchange translation resulted in a reduction of $0.02 per share also on an adjusted basis for Q4 and $0.05 per share for the full-year.
Now please turn to Slide 10 for a look at free-cash flow. For the year, our free-cash flow grew 4.2%, driven primarily by improved operating income and net income. Our free-cash flow definition, like other peers, excludes changes in working capital. For full-year 2024, our working capital improved once again by 50% to a use of $231 million, as you can see on Slide 18. We expect our strong performance will continue and bring us back over-time toward our historically neutral annual level.
Regarding our primary uses of free-cash flow for full-year 2024, we used $553 million of cash to pay for dividends to common shareholders and another $85 million for dividends to non-controlling interest shareholders, both roughly the same level as 2023. Our capital expenditures were $141 million. Levels were higher in 2024, reflecting ongoing investments in flywheel, our strategic technology platform initiatives and investments in our facilities. Total acquisition payments, which include earn-out payments and the acquisition of additional non-controlling interests were $998 million, which primarily reflects the acquisition at the beginning of the year of flywheel for $845 million, net of cash acquired and the late September acquisition of Leappoint.
Finally, our share repurchase activity was $371 million, excluding proceeds from stock plans of $102 million, which is in-line with our expectation that repurchases will be lower than our recent historical average of approximately $600 million due to the Flywheel acquisition. For full-year 2025, we expect to return to the $600 million repurchase level. Slide 11 is a summary of our credit, liquidity and debt maturities. At the end of 2024, book-value of our of our outstanding debt was $6 billion, up from the end of 2023. Changes during the year included the issuance of $600 million, 3.7% euro notes related to the Flywheel acquisition as well as the issuance of $600 million, 5.3% US dollar notes, which was used for most of the repayment of our $750 million, 3.65% US dollar notes in November.
Looking-forward, we have no maturities in 2025 and expect to address our April 2026 maturities after the expected closing of the IPG acquisition in the second-half of 2025. We estimate net interest expense to increase in Q1 of 2025 by approximately $7 million, reflecting the full-quarter impact of the notes we issued in February of 2024 and an expected increase in pension-related interest expense.
We also estimate that net interest expense will increase by $15 million to $20 million for the full-year, primarily related to lower estimates of interest income beyond Q1. Cash equivalents and short-term investments at September 30 were $4.3 billion, in-line with levels at the end of 2023. We continue to maintain an undrawn $2.5 billion revolving credit facility, which backstops our $2 billion US commercial paper program. We will assess our revolver capacity in connection with the closing of the proposed IPG acquisition.
Slide 12 presents our historical returns on two important performance metrics for the 12 months ended, 31 December 2024. Omnicom's return on invested capital was 25%. Our return-on-equity was 38%, both of which consistently reflect our strong performance and strong balance sheet. Slide 13 is a summary of the potential IPG acquisition, which highlights what we believe are the very compelling merits of the transaction. As John discussed, we believe the combination will drive exceptional future growth opportunities. In closing, 2024 was a very solid year for.
We delivered organic revenue growth of 5.2%, adjusted EBITDA growth of 6.1% and adjusted EPS growth of 5.5%. We made important investments in our platforms while maintaining our strong adjusted EBITDA margin level. Our free-cash flow grew by over 4% and we significantly reduced our use of operating capital. We executed two key financings, closed on strategic acquisitions and announced the transformative acquisition of IPG.
I will now ask the operator to please open up the lines for questions-and-answers. Thank you.
