The 18-24 Month Portfolio Company Leadership Clock

There is a clock that starts the day a private equity firm closes a deal, and almost nobody hands the operating company's CEO a copy of it. By month eighteen, most boards already know whether they're going to use it — the wind-down on the current CEO. By month twenty-four, over half of the CEOs who are going to leave already have.

AlixPartners' 11th Annual Private Equity Leadership Survey, fielded from October through December 2025 and drawing on more than 420 PE firm and portfolio company leaders, found that nearly two-thirds of PE firms replace portfolio company CEOs during the holding period. Only 9% of firms said they "rarely" replace a CEO. This is not an edge case in PE ownership. It is closer to the median outcome.

Separate research from Russell Reynolds, published via Harvard Law School's Forum on Corporate Governance in September 2026, sharpens the timing: 75% of CEOs who exit a PE-owned company do so after a change in control, and 54% of those exits land one to two years after the transaction closes. Read the two studies together and a clock appears — not a vague sense that PE-backed CEOs turn over a lot, but a specific window in which the decision gets made.

The clock, month by month

• Month 0 — CloseThe CEO who ran the company into the deal is, in most cases, still the CEO who runs it out of close. The value creation plan is set. Expectations are set with it, often more aggressively than the diligence period tested.
• Months 1–12 — The evidence window opensReporting cycles, board interactions, and the first operational milestones start generating evidence — not about whether the thesis is right, but about whether the incumbent CEO can execute it. This is the period Russell Reynolds' research describes as providing "the evidence required to assess the investment thesis and the incumbent leadership."
• Months 12–18 — The decision windowAlixPartners and multiple other PE operating-partner surveys place the peak of CEO turnover risk here — after management has had roughly 12 to 18 months to execute against the plan, and boards have enough evidence to act on a verdict rather than a hunch.
• Months 18–24 — Where the exits land54% of CEO exits following a change in control occur in this window, per Russell Reynolds. If a replacement is coming, this is when it most often actually happens — not as a sudden move, but as the visible endpoint of a decision the evidence window already made.
• Beyond month 24CEOs who make it past the two-year mark without replacement are meaningfully more likely to run the company to exit. The clock doesn't reset — it mostly stops ticking.

The cost of getting this wrong is not confined to the CEO seat. AlixPartners' broader research finds 83% of PE executives say unplanned CEO turnover lengthens the holding period, and nearly half say it directly reduces returns. A CEO change inside the value creation window doesn't just cost a search fee — it resets the operating clock the entire fund model was built around.

The eighteen-month window isn't when boards lose patience. It's when they finally have enough evidence to act on the patience they ran out of months earlier.

What this means for how the CEO gets chosen in the first place

If two-thirds of PE-backed CEOs face a real replacement decision within the holding period, and the evidence for that decision is mostly gathered in the first 12 to 18 months, then the placement decision at close is being asked to predict something specific: not just whether this person can run the company today, but whether they are the right operator for what the company needs to become by month 18 — execution against an aggressive plan, in a structure and culture that may look very different from what got tested in diligence.

That is precisely the distinction we've written about between an AI Operating Partner and a fractional CAIO answering different questions for a portfolio company — and it's the same distinction that separates a CEO placement built for the deal from one built for the eighteen-month mark. A search that only verifies fit against the current org chart and the current thesis is testing exactly the population most likely to fail the evidence window: operators suited to where the company is, not where the plan requires it to be.

The bridge most firms underuse

When the evidence window does surface a gap — a CEO who is right for today's operations but untested against the next eighteen months of the plan, or a seat that opens mid-hold with no obvious internal successor — the reflex is often a rushed full-time search under board pressure, the same rushed conditions AlixPartners identifies as extending the very holding periods everyone is trying to protect. A fractional or interim leadership bridge exists specifically for this window: it buys the operating continuity a stalled quarter can't afford while a properly-scoped search — one built around the evidence the first twelve months actually produced, not the assumptions the deal was priced on — replaces a rushed one.

The pattern we've traced before in the year-two CEO exit holds up again here with independent data: the second year of a PE hold isn't an unlucky moment for leadership change. It's the point where the evidence the fund needed all along finally becomes undeniable — and the companies that treat the eighteen-month mark as predictable, rather than as a surprise each time, are the ones that use the clock instead of being caught by it.