The landscape of American corporate governance has undergone a seismic shift as shareholder activism targeting mergers and acquisitions (M&A) transitions from a fringe tactic to a primary strategy for institutional investors. A comprehensive new report titled "Deals in Dispute," released by Diligent Market Intelligence in association with the law firm Seward & Kissel, reveals that opposition to announced deals has become a durable and increasingly successful feature of the public-company environment. Analyzing nearly 300 activist demands directed at US-listed companies since 2015, the report highlights a significant escalation in both the frequency and the efficacy of these campaigns, with activist success rates in 2025 reaching their highest levels since 2018.
This trend underscores a growing boldness among shareholders who are no longer content to simply vote on proposed transactions but are instead actively working to block, renegotiate, or significantly alter the terms of corporate exits and consolidations. As boards of directors navigate an era of high interest rates, regulatory scrutiny, and market volatility, the "Deals in Dispute" report serves as a critical barometer for the friction inherent in modern deal-making.
The Evolution of M&A Activism: From 2015 to 2025
The trajectory of M&A activism over the past decade reflects a maturation of the activist playbook. In the mid-2010s, activism was often synonymous with "balance sheet" demands—pushing for stock buybacks or dividend increases. However, the data provided by Diligent indicates a pivot toward transactional activism. Between 2015 and 2019, activists increasingly focused on "bumpitrage," a strategy where a minority shareholder acquires a stake in a target company after a deal is announced and then agitates for a higher purchase price.
The period between 2020 and 2022 saw a brief lull in aggressive M&A opposition, largely due to the uncertainties of the global pandemic and a temporary slowdown in traditional M&A volume. However, as the market stabilized in 2023 and 2024, activism returned with renewed vigor. By 2025, the success rate of activists—defined as achieving a price increase, successfully blocking a deal, or forcing a change in deal structure—climbed to levels not seen in seven years. This resurgence is attributed to better-capitalized activist funds and a more skeptical institutional investor base that is increasingly willing to align with activists if the premium offered by an acquirer is perceived as inadequate.
Statistical Insights and Success Metrics
The Diligent report draws upon extensive voting and governance datasets to quantify the impact of these disputes. Of the nearly 300 demands analyzed since 2015, a significant portion occurred within the last 24 months. The data suggests that activists are becoming more surgical in their targets, focusing on companies where the "control premium" is arguably below historical norms or where the strategic rationale for the merger is poorly articulated by management.
One of the most striking findings is the success rate of 2025. While historical success rates for blocking a deal entirely remain relatively low—given the legal and financial hurdles involved—the success rate for "partial wins," such as forcing a price "bump," has spiked. According to the report, activists are now successfully extracting higher valuations in nearly one out of every four contested deals. Furthermore, the use of the Universal Proxy Card (UPC), mandated by the SEC in late 2022, has empowered activists to threaten board seats more effectively during an M&A dispute, providing them with additional leverage to force concessions from the incumbent board.
Chronology of the Contested Deal Era
To understand the current state of M&A disputes, it is essential to view the timeline of regulatory and market shifts that have facilitated this environment:
- 2015-2017: The rise of specialized activist funds. Activists begin to move beyond simple cost-cutting demands to questioning the long-term value of proposed "mega-mergers."
- 2018: A peak year for activism. High-profile battles, such as the opposition to the Fujifilm-Xerox merger, demonstrate that activists can successfully kill deals that they deem detrimental to shareholder value.
- 2019-2021: The "Bumpitrage" Era. Activists focus on price discovery, often successfully forcing acquirers to raise their bids by 5% to 15% to secure shareholder approval.
- 2022: Regulatory Shift. The SEC introduces the Universal Proxy Card rules, fundamentally changing how proxy contests are fought and making it easier for shareholders to vote for individual activist nominees.
- 2023-2024: Economic Headwinds. Rising interest rates make financing more expensive, leading activists to argue that "fire sales" are occurring and that boards should wait for better market conditions rather than selling at a cyclical low.
- 2025: The New High. Activist success rates hit a seven-year peak as institutional investors (like BlackRock and Vanguard) become more willing to vote against management in contested M&A scenarios.
Strategic Drivers Behind Activist Demands
The "Deals in Dispute" report identifies several recurring themes that drive activist opposition. The most common is the "undervaluation" argument. In these cases, activists present alternative valuations, often supported by independent forensic accounting, to suggest that the target company’s board has failed in its fiduciary duty to maximize shareholder value.
Another emerging driver is "strategic misalignment." This occurs when an activist argues that a company should be broken up into separate entities rather than sold as a whole, or when they oppose a "merger of equals" on the grounds that the resulting synergy projections are unrealistic.
The report also highlights the role of ESG (Environmental, Social, and Governance) factors. In some recent disputes, activists have opposed acquisitions by companies with poor environmental records or governance structures, arguing that such deals pose long-term reputational and financial risks to the target company’s shareholders.
The Role of Boards and Professional Preparedness
A critical component of the report produced by Diligent and Seward & Kissel is the advice offered to corporate boards. The rise in contested M&A means that "business as usual" is no longer a viable strategy for boards considering a sale.
"Contested M&A is no longer a niche concern," the report notes. This statement reflects the reality that any deal involving a US-listed company is now subject to intense scrutiny. Legal experts from Seward & Kissel emphasize that boards must conduct exhaustive "market checks" before agreeing to a deal. This involves not only looking for the highest bidder but also preparing a robust defense that anticipates activist critiques.
Professional reactions to the report suggest that boards are being encouraged to engage with their top shareholders long before a deal is ever announced. By understanding shareholder sentiment and expectations regarding valuation, boards can preemptively address the concerns that activists typically exploit. Failure to do so can lead to costly delays, litigation, or the total collapse of a strategic initiative.
Broader Market Implications and Analysis
The implications of increased M&A activism extend far beyond the individual companies involved. There is a growing concern among some market analysts that the high success rate of activists may have a "chilling effect" on M&A activity. If potential acquirers fear that every deal will result in a protracted and expensive legal or proxy battle, they may be less inclined to pursue acquisitions, particularly of companies with a history of activist involvement.
Conversely, some argue that this trend is a healthy development for the market. By holding boards accountable, activists ensure that deals are only completed when they truly serve the interests of the shareholders. This prevents "empire building" by CEOs and ensures that capital is allocated more efficiently across the economy.
The data from 2025 suggests that we are entering a "new normal" where the announcement of a deal is merely the beginning of a public negotiation. The "Deals in Dispute" report indicates that the gap between the board’s perception of value and the shareholders’ expectation of value is widening, fueled by a more transparent and data-rich investment environment.
Conclusion: A Durable Feature of the Landscape
As the 2026 fiscal year approaches, the findings from Diligent Market Intelligence and Seward & Kissel serve as a stark reminder that the power dynamics in corporate America have shifted. The activist success rates of 2025 are not an anomaly but the result of a decade-long evolution in shareholder engagement and regulatory reform.
For companies, the message is clear: transparency, rigorous valuation, and proactive shareholder communication are the only defenses against the rising tide of M&A activism. For investors, the "Deals in Dispute" report validates the efficacy of activism as a tool for value creation. As long as there is a perceived gap between a deal’s price and its potential value, activists will continue to step into the fray, turning the M&A process into a high-stakes arena of public and financial contestation.
