The Evolution of M&A Activism: From 2015 to the Present
The trajectory of contested M&A has been shaped by broader economic cycles, regulatory shifts, and the increasing sophistication of activist hedge funds. In the mid-2010s, activism was often characterized by "bumpitrage"—a strategy where investors would acquire stakes in a target company after a deal was announced, then agitate for a higher price. While this remains a staple of the activist toolkit, the strategies identified in the Diligent report suggest a more nuanced approach.
Between 2015 and 2018, activism was largely driven by a period of low interest rates and high deal volumes. Activists during this era focused on "sweetening" the pot. However, the data shows that following 2018, there was a brief cooling period as boards became more adept at defense and the global pandemic temporarily stalled the M&A market. The resurgence observed in 2024 and 2025 is distinct; it is occurring in an environment of higher capital costs and increased regulatory scrutiny from the Federal Trade Commission (FTC) and the Department of Justice (DOJ).
The report highlights that the current wave of activism is more "durable." This suggests that shareholders are no longer just looking for a quick price hike but are willing to scuttle deals entirely if they believe the strategic rationale is flawed or if the company is being sold at a cyclical low. The rise in success rates in 2025 indicates that activists are becoming more selective and effective in their campaigns, often winning over larger institutional passive investors who were traditionally more inclined to support management.
Key Findings: Success Rates and Shareholder Sentiment
The Diligent and Seward & Kissel report provides a data-driven look at the success of these campaigns. Since 2015, the volume of demands has remained steady, but the "win rate" for activists—defined as either a deal being blocked, a price being significantly raised, or a change in deal terms—has spiked. In 2025, this rate reached a seven-year high.
Several factors contribute to this increased efficacy:
- Enhanced Data Analytics: Activists are utilizing sophisticated data to identify "value gaps" long before a deal is even rumored.
- Institutional Alignment: There is a growing trend of alignment between aggressive activist funds and traditionally conservative "long-only" institutional investors. When an activist presents a compelling case that a board has undersold a company, major asset managers are increasingly likely to vote against the transaction.
- Transparency Requirements: Recent changes in proxy voting rules and disclosure requirements have made it easier for activists to communicate their platform to the broader shareholder base.
The report notes that nearly 300 demands have been tracked since 2015, providing a statistically significant sample size to conclude that M&A activism is a permanent fixture of the corporate governance environment. Boards can no longer treat the "say-on-pay" or "say-on-deal" votes as mere formalities.
The Chronology of a Contested Deal
Understanding the timeline of a contested merger is essential for boards and investors alike. The Diligent report outlines a typical lifecycle for these disputes:
- The Quiet Phase: Before an activist goes public, they often build a position and engage in private discussions with the board. The report suggests that many "wins" for activists happen in this phase and are never made public.
- The Announcement and Immediate Reaction: Once a deal is publicly disclosed, the activist issues a public letter or filing (such as a Schedule 13D) outlining their grievances. This usually focuses on the "inadequacy" of the premium or the lack of a robust "go-shop" period.
- The Campaign for Proxies: Both the company and the activist engage in a "ground war" for shareholder votes. This involves hiring proxy solicitors, issuing white papers, and meeting with influential proxy advisory firms like ISS and Glass Lewis.
- The "Bump" or the Break: As the vote nears, the board faces a choice: stick to their guns and risk a failed vote, or negotiate with the activist for a price increase (the "bump"). The data shows that in 2025, boards are increasingly choosing to negotiate rather than risk total deal failure.
- Post-Deal Litigation: Even if a vote passes, activists may pursue appraisal rights in court, seeking a judicial determination of the "fair value" of their shares, which can often exceed the deal price.
Strategic Implications for Corporate Boards
For corporate directors, the findings in the "Deals in Dispute" report serve as a call to action. The era of the "uncontested exit" is largely over for mid-cap and large-cap U.S. companies. The report suggests that boards must adopt an "activist mindset" during the deal-making process.
Seward & Kissel experts emphasize that boards must be able to demonstrate a rigorous process. This includes documented evidence that all strategic alternatives were explored, not just the sale to a preferred buyer. Furthermore, the "fairness opinion" provided by investment banks is receiving more scrutiny; activists are increasingly dissecting the methodology of these opinions to find flaws in the valuation.
Preparation involves:
- Proactive Shareholder Engagement: Maintaining open lines of communication with top investors year-round, not just when a deal is on the table.
- Vulnerability Assessments: Conducting internal "stress tests" to see how an activist might critique a potential transaction.
- Strategic Communications: Developing a clear narrative that explains why a deal is in the long-term interest of shareholders, particularly if the immediate premium appears low.
The Broader Impact on the M&A Market
The rise in contested M&A has significant implications for the broader economy and the private equity sector. When activists successfully block deals or demand higher prices, it can lead to "deal fatigue." Potential acquirers may become more hesitant to enter the market if they believe they will be held hostage by a minority group of shareholders after the announcement.
However, from a governance perspective, this trend can be seen as a healthy check on "empire-building" by CEOs or "fire sales" by boards looking for an easy exit. The Diligent report suggests that the increased success of activists is forcing a higher standard of discipline across the board.
Moreover, the regulatory environment cannot be ignored. The FTC’s more aggressive stance on antitrust means that the "time to close" for many deals has extended. This longer window provides activists with more time to build a case and organize a campaign. The intersection of regulatory delay and activist agitation has created a "perfect storm" for contested M&A.
Expert Reactions and Market Outlook
Industry analysts reacting to the Diligent Market Intelligence findings suggest that 2026 will likely continue this trend. As companies grapple with the "new normal" of higher interest rates, those with lagging stock prices will remain prime targets for activists who believe they can extract more value through a contested sale or a breakup of the company.
Legal experts from Seward & Kissel note that the "success" of activists in 2025 is likely to embolden more players to enter the space. We are seeing a diversification of activists—it is no longer just the well-known "names" but also smaller, sector-specific funds that are launching highly technical challenges to M&A deals.
The report concludes that "Deals in Dispute" are no longer the exception but a foreseeable risk that must be priced into every transaction. For shareholders, this represents a golden age of engagement where their voices—and their votes—have more leverage than ever before. For boards, it represents a more demanding and transparent era of fiduciary responsibility where every decision is subject to intense, data-driven public scrutiny.
As the market moves toward 2026, the lessons from the nearly 300 demands analyzed in this report will serve as the blueprint for the next generation of corporate governance and M&A strategy. The "Deals in Dispute" report stands as a definitive record of this transformation, marking a period where the boardroom and the trading floor have become inextricably linked in the fight for corporate value.
