The accounting industry is in the middle of a structural reset driven by private equity capital, and the Grant Thornton acquisition of CBIZ is the clearest signal yet that the reset is accelerating. On July 29, 2026, Grant Thornton Advisors announced a definitive agreement to acquire CBIZ in an all-cash transaction valued at $5 billion. The deal is the largest of its kind in public accounting in more than 25 years, the last comparable event being the formation of PricewaterhouseCoopers from the merger of Coopers & Lybrand and Price Waterhouse in 1998.
Both Grant Thornton and CBIZ have built strong organizations with talented professionals who have served the middle market with real depth and commitment. This post is not a criticism of those people or their work. It is an honest look at what large-scale accounting firm consolidation does to the client relationship infrastructure those professionals have spent years building, and what that means for independent firms that compete on continuity and access. Understanding how accounting firm consolidation affects client behavior is the starting point for any firm that wants to grow in this environment.
The Double Disruption: 35,000 Clients in 24 Months
The timeline of recent transactions reveals a compounding vulnerability in the market. In November 2024, CBIZ closed its $2.3 billion acquisition of Marcum’s non-attest business, absorbing an estimated 35,000 clients into its operations. Less than two years later, those same clients received news of a second major ownership change.
This means a significant portion of the middle-market client base is now facing its second significant integration event in under 24 months. While CBIZ reported strong overall client retention following the initial Marcum transaction, and noted that independence-related attrition came in at or better than modeled, the second major change in a short period carries a different kind of risk. Industry research on professional services mergers indicates that average client attrition runs around 5 percent annually under normal conditions. Successive transitions amplify that risk as clients grow weary of shifting primary contacts, changing billing systems, and evolving service models.
The clients who already navigated one cultural and operational transition are now bracing for another. This double disruption is the defining feature of the current accounting firm consolidation wave: it is not one change, it is two changes compressing into the same client relationship in under two years. That compression creates a critical inflection point where loyalty is tested and alternative service providers become genuinely viable options for the first time.
What the CBIZ Filings Actually Say About Client Risk
One of the most credible data points in any accounting firm consolidation story is the company’s own SEC disclosure. The client retention risk in this deal is not speculation. CBIZ disclosed it directly to shareholders in its 2025 annual report filed with the SEC. The filing states that the company is “dependent on its existing client base and its ability to retain and expand relationships with those clients,” and that clients “may terminate engagements with little or no notice and without penalty, which may result in unexpected declines in revenue or unexpected costs.” The filing also warns that “failure to maintain reputation and brand could impact the ability to attract and retain clients,” and that the business “could be adversely affected if the non-attest business assets we acquired from Marcum do not perform to our expectations.”
These are not generic legal disclaimers. They are the specific, named risks CBIZ disclosed to shareholders in its most recent 10-K, filed just months before announcing a second major transaction on top of an integration that was still being completed. The company’s own risk language tells you exactly where the pressure points are, and where independent firms should be looking.
How Private Equity Changes the Operating Model
The influx of private equity into the accounting profession changes more than ownership structures. It fundamentally alters the operating model. In 2025 alone, over 170 private equity-backed CPA firm transactions closed, more than doubling the volume of the previous year. As of early 2026, almost half of the top 30 United States CPA firms carry some form of private equity investment.
The drive for margin improvement is sound business practice. The question is whether it is executed in a way that preserves the relationship infrastructure clients depend on. When cost reduction moves faster than cultural integration, the internal friction that follows tends to surface in the places clients notice most: slower response times, reduced partner availability, and teams competing for credit rather than collaborating on solutions. When New Mountain Capital made its majority investment in Grant Thornton Advisors in May 2024, the firm transitioned to an alternative practice structure and reduced its workforce by approximately 350 employees. Observed patterns across PE-backed professional services firms suggest that the period immediately following a second major acquisition is when these pressures become most visible to clients.
This is not a prediction that the combined firm will fail to serve its clients well. Many of the professionals inside both organizations are exceptional. The structural reality is that leadership bandwidth is finite, and a $5 billion integration demands an enormous amount of it.
Leadership Distraction Creates Market Openings
During a transaction of this scale, senior partners and practice leaders at both combining firms will spend significant time on deal closure, systems integration, compensation alignment, and cultural decisions. This is the predictable cost of accounting firm consolidation at this speed: internal focus displaces client focus, and the gap shows up in the places clients notice most.
The company is now entering a second major integration before the first one was fully absorbed. As the filing language discussed above makes clear, CBIZ itself acknowledged the risk that acquisitions “may prove disruptive and could result in the combined business failing to meet expectations.” That disclosure was written about the Marcum deal. The Grant Thornton transaction layers a second set of integration demands on top of those still-open risks. When leadership is looking inward, clients who value consistent senior-level relationships become more open to conversations with independent firms.
Talent movement almost always accompanies these mega-deals. Departing partners and directors frequently bring, or later attract, their strongest client relationships. For independent firms, the opportunity is twofold: acquiring dissatisfied clients directly, and recruiting professionals who prefer a less centralized, less PE-driven environment.
The RSM Question: What Does Number Five Mean Now?
There is a competitive subplot here worth watching. RSM US has held the number five position on the Accounting Today Top 100 for 19 consecutive years. According to the most recent IPA rankings, RSM generated approximately $4.2 billion in U.S. net revenue during its most recent fiscal year. The combined Grant Thornton and CBIZ entity is expected to generate more than $5 billion in domestic revenue upon close, displacing RSM from a position it has held for nearly two decades.
That is roughly an $800 million domestic revenue gap. RSM US formalized a transatlantic partnership with RSM UK, effective January 1, 2026, creating a combined platform with approximately $5 billion in aggregate annual revenue. However, both the IPA Top 500 and Accounting Today Top 100 rank firms on U.S. net revenue only. RSM UK’s revenue does not count toward RSM’s domestic ranking. The transatlantic partnership does not close the gap.
RSM already positions itself as the preeminent middle-market firm in the United States. That positioning alone does not close an $800 million revenue gap. The realistic paths are domestic acquisitions, entry into a new service category that generates recurring revenue at scale, or both. RSM has already signaled its direction. In June 2025, it announced a $1 billion technology investment to accelerate its AI strategy, a move that points toward advisory and managed services revenue streams that traditional accounting firms have not historically owned. Whether RSM uses that platform as the foundation for a genuinely new service line, or whether it pursues domestic acquisitions to close the gap more directly, remains to be seen. How aggressively RSM builds on these options will be one of the most consequential strategic decisions in accounting firm consolidation over the next 24 months. A firm of RSM’s quality and competitive track record does not cede a 19-year ranking quietly.
For independent firms, the RSM response matters. If RSM accelerates U.S. acquisition activity to close the gap, the consolidation wave intensifies further and the window for independent firms narrows. That makes moving now, while leadership at the combining firms is focused inward, the right time to act.
The Strategic Pivot for Independent Firms
The middle market still contains a large population of clients who prefer firms that feel accessible and less process-heavy than the emerging mega-platforms. Accounting firm consolidation at this scale creates a predictable pattern: clients who valued personal access begin to feel like account numbers, and that feeling creates a window. Independent firms generating between $5 million and $30 million in revenue are uniquely positioned to capture this market share. As detailed in our analysis of Accounting Firm Growth: 3 Ways Independent CPAs Can Beat the Capacity Trap, smaller firms can use their agility to provide superior advisory services that large platforms struggle to replicate at scale.
To capitalize on this window, independent firms must execute a precise go-to-market strategy. Outreach must lead with empathy and continuity rather than criticizing the combining firms. Messaging should focus on what the client values most: direct access to partners, rapid responsiveness, deep industry knowledge, and long-term relationship stability. The promise that “you will still know your partner and the team that works on your account” resonates powerfully with clients experiencing integration fatigue.
Firms must also be prepared for longer decision cycles. Many clients will wait to see how the integration unfolds before moving, making consistent, value-driven follow-up essential. The clients who move first are often those with the strongest existing relationships with a partner who has already left or is planning to leave. Tracking talent movement at the combining firms is as important as tracking the client list. For a deeper look at aligning your outreach to capture this opportunity, review our guide on Surviving the Consolidation Wave: Aligning Sales and Marketing Data to Accelerate Firm Growth.
Large combinations create scale for the buyers. They also create temporary openings for firms that compete on trust and continuity. The Marcum-to-CBIZ-to-Grant Thornton sequence is the most compressed accounting firm consolidation event the middle market has experienced in a generation. It raises the probability that some clients will actively evaluate alternatives. Firms that move thoughtfully, with clear positioning and genuine relationship focus, stand to gain meaningful, sticky clients during this period.
Frequently Asked Questions
Why does the CBIZ and Grant Thornton deal matter to independent accounting firms? The acquisition is the largest single accounting firm consolidation event in over 25 years. It creates a period of distraction and potential service disruption for tens of thousands of middle-market clients, making them more receptive to independent firms that offer relationship continuity and direct partner access. CBIZ’s own SEC filings confirm that client retention is a named risk factor in large integrations.
How does private equity involvement change accounting firm culture? Private equity investment typically introduces strict operational metrics and utilization targets. When cost reduction moves faster than cultural integration, the internal friction that follows tends to surface in the places clients notice most: slower response times, reduced partner availability, and teams competing for credit rather than collaborating on solutions.
What is the most effective way to approach clients affected by accounting firm consolidation? Outreach should focus on empathy and service clarity rather than criticism of the combining firms. Emphasize your firm’s stability, dedicated service teams, and long-term relationship approach. Track talent movement at the combining firms closely, as departing partners are often the first signal that their clients are ready to have a conversation.
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