Our fourth quarter adjusted EBITDA was $41.3 million, an increase of $2 million, or 5.1% from the fourth quarter of 2022. Fourth quarter adjusted EBITDA margin was 23.4% flat compared to the fourth quarter of 2022 as higher investment companies transactional and software solutions net sales volume and the impact of cost control initiatives were offset by lower capital markets transactional net sales and incremental investments to accelerate the company’s transformation. Turning now to our fourth quarter segment results. Net sales in our Capital Markets Software Solutions segment were $48 million, an increase of 12.4% on an organic basis from the fourth quarter of last year, driven by the strong growth in our virtual data room offering Venue, which was up $6.3 million, or 26% year-over-year, and achieved record quarterly sales.
Venue’s outstanding performance in the quarter was driven by a higher room count, an increase in volume within existing rooms, and higher pricing. On a full year basis, Venue delivered approximately $110 million in net sales and grew nearly 11% versus full year 2022 and is a main contributor to the growth of our recurring and reoccurring offerings in 2023. Venue’s performance has been consistent primarily as a result of stable demand from both announced and unannounced deals, as well as across public and private companies alike, despite some volatility inherent in the broader M&A market in terms of completed deals. Net sales of our recurring compliance product active disclosure, including File 16 declined approximately 2% in the fourth quarter, driven primarily by lower Section 16 filing activity, which was down nearly 16%.
In the quarter, we experienced lower demand for beneficial ownership filings as a result of a weak IPO market as well as elevated churn as we transition clients to a subscription based model. In addition, following the decommissioning of the legacy AD3 platform, we had fewer clients on the new AD platform as a result of the expected elevated customer churn rate during the transition. A lower customer count in conjunction with the impact of SPAC liquidations, normal customer churn and the ongoing weakness in IPO activity resulted in a modest decline in subscription revenue in the quarter. The decline in subscription revenue was partially offset by price increases, higher service revenue, and new customer wins. During the fourth quarter, we made continued progress to expand the adoption of active disclosure.
Following a sequential increase in net client count during the third quarter, we realized the sequential increase in client count again during the fourth quarter. The momentum in client count growth coupled with product enhancements we have released create a strong foundation for sales growth in 2024 and beyond. We expect ActiveDisclosure’s growth rate in the second half of 2024 to be stronger than the first half as some of the headwinds we experience in 2023 continue to play out in the first part of 2024. Adjusted EBITDA margin for the segment was 26.5%, an increase of approximately 530 basis points from the fourth quarter of 2022, primarily due to higher net sales volumes and cost control initiatives partially offset by higher selling expenses as a result of increased net sales and higher incentive compensation expense.
Net sales in our Capital Markets Compliance and Communications Management segment were $68.3 million, a decrease of $5.1 million or 6.9% from the fourth quarter of 2022, primarily driven by lower event-driven or transactional net sales. We recorded approximately $50 million in fourth quarter transactional revenue in line with our expectations. Similar to the trends we experienced during the first nine months of the year, the demand environment for equity transactions remained soft in the fourth quarter, though the rate of decline continued to moderate as we overlap periods of weak demand in 2022. Adjusted EBITDA margin for the segment was 30.7%, a decrease of approximately 120 basis points from the fourth quarter of 2022. The decrease in adjusted EBITDA margin was primarily due to lower transactional sales volumes partially offset by cost control initiatives.
Net sales in our Investment Company Software Solutions segment were $25.7 million, an increase of 1.6% versus the fourth quarter of 2022, primarily driven by growth in the ArcDigital and ArcRegulatory modules within Arc Suite. As expected, the growth rate in the fourth quarter was slower compared to the third quarter of this year, which was aided by higher one-time services and support revenue. On a full year basis, total Arc Suite delivered approximately $107 million in revenue and grew 7.4% year-over-year, driven by growth in subscription revenue as a result of the continued strong adoption of Arc Suite within investment companies. Based on the incremental revenue from Tailored Shareholder Reports, we expect stronger Arc Suite revenue growth starting in the second half of 2024.
Adjusted EBITDA margin for the segment was 31.5%, a decrease of approximately 530 basis points from the fourth quarter of 2022. The decrease in adjusted EBITDA margin was primarily due to higher product development and technology investments in support of growth opportunities, such as Tailored Shareholder Reports and higher incentive compensation expense partially offset by cost control initiatives. Net sales in our Investment Companies-Compliance and Communications Management segment were $34.5 million, an increase of $8.9 million or 34.8% from the fourth quarter of 2022, primarily driven by higher event driven revenue from a large mutual fund special proxy project. Adjusted EBITDA margin for the segment was 30.1%, an increase of approximately 860 basis points from the fourth quarter of 2022.
The increase in adjusted EBITDA margin was primarily due to higher net sales volumes and the impact of cost control initiatives, including continued synergies from our print platform consolidation partially offset by higher incentive compensation expense. Non-GAAP unallocated corporate expenses were $10.9 million in the quarter, an increase of $2.8 million from the fourth quarter of 2022, primarily driven by an increase in expenses aimed at accelerating our transformation and higher incentive compensation expense, partially offset by the impact of cost control initiatives. Free cash flow in the quarter was $56 million, a decrease of $2.5 million compared to the fourth quarter of 2022. The year-over-year decline in free cash flow is primarily driven by higher capital expenditures related to investments in our software products and the underlying technology to support them, partially offset by an increase in adjusted EBITDA.
