New Diligent Market Intelligence (DMI) research shows that opposition to announced deals is no longer a niche feature of the market. In the 10-year period through 2025, activists advanced just under 300 oppose-sale demands at U.S.-based companies, with activity elevated since 2020 and success rates reaching their highest point since 2018 in 2025.
That shift should change how boards think about transaction readiness. The question is no longer only whether a company can get a deal signed, but whether it can defend that deal against scrutiny over price, process, timing and strategic logic.
Contested deals are becoming a more practical risk
One of the clearest takeaways from the report is that oppose-sale campaigns can work. Activists achieved their objectives in 37.5% of oppose-sale demands advanced in 2025, the highest recorded success rate since 2018.
Proxy advisor recommendations also still matter. The average vote for an opposed merger was less than 54% when Institutional Shareholder Services (ISS) recommended voting against it, compared with more than 91% when ISS supported the deal.
The report’s case studies show what that looks like in practice using two recent examples. STAAR Surgical’s sale to Alcon failed to win shareholder support after Broadwood argued the deal undervalued the company and reflected a flawed process, while Core Scientific shareholders voted down the company’s proposed merger with CoreWeave after critics argued the terms failed to capture the upside in AI infrastructure valuations.
What makes a deal vulnerable
As Randall Adams from Seward & Kissel, the law firm that sponsored our report, explains, the transactions most likely to attract public opposition usually suffer from more than a debate over price alone. They often raise deeper questions about process, such as whether the market check was broad enough, whether conflicts were adequately addressed or whether the company’s future potential was weighed carefully enough.
Activist campaigns may begin with concerns over valuation and strategy because it is the clearest way to rally other shareholders, but they can quickly escalate. The rollout of a deal necessitates disclosures about process, governance, and incentives through the proxy statement, which can fuel an activist campaign if not carefully considered. If the board’s response to shareholder or proxy advisor engagement feels incomplete or unpersuasive, concerns about price can quickly evolve into a broader collapse in shareholder support.
Seward & Kissel’s Mark Garibyan adds another timely warning: public opposition is no longer limited to the best-known activist funds. Influence today is increasingly about persuasion, message discipline and the ability to build trust with other shareholders, not simply the size of a stake or the familiarity of a name.
That aligns with the report’s data showing that occasional activists accounted for 52% of demands and were at least partially successful 37% of the time.
And the longer a CEO has been at the helm, the less likely that activists can break up a deal to sell the company. Oppose-sale campaigns succeeded 32.7% of the time at companies where the CEO had been in post for less than 10 years. Past 20 years, that fell to 15.4%. Corporate defenses such as staggered boards, special meeting rights and poison pills, showed far more muted effects.
The board’s role starts before the vote
The most useful lesson for directors may be that activism preparedness begins well before a transaction is announced. The report argues that boards need to pressure-test whether they have chosen the best available path, whether alternatives were fully considered and whether they can defend both the economics and the governance of the transaction.
That point becomes even sharper when considered alongside Diligent Institute’s October 2025 transaction readiness research. In that survey, only 7% of respondents named shareholder engagement or activism as one of their top three transaction readiness risks, yet 31% said they wanted better communication, oversight or support at the board level.
Even assuming that the majority of executives are happy with their boards’ involvement, the remainder must work more closely with advisors, identify investors with a history of activism in their stock, and carefully consider the rollout of deals.
Transaction readiness now includes narrative, governance and systems
The October report also found that economic uncertainty was cited by 49% of respondents as resulting in delayed deals, 46% in adjusted financial models and 40% in enhanced due diligence.
In other words, many organizations were already operating in a more cautious environment heading into 2026. What this new DMI report adds is that this caution must extend beyond diligence and valuation models to include the case for shareholder backing.
Boards that want support cannot treat communications as a final-stage exercise. Transaction readiness is increasingly about being ready to defend a deal with the appropriate data alongside demonstrable board-level oversight and conviction to persuade shareholders that the future you are offering is more credible than the alternatives.
