The zombie-fund number is the headline. Assets stuck in North American zombie funds, vehicles that have outlived their intended life and keep holding companies they cannot sell, rose from $372 billion in 2021 to a record $441 billion in 2024. More than half of limited partners, the pensions and endowments that supply the capital, expect the number of zombie funds in their portfolios to grow over the next two years. But the headline is a symptom. The disease is a metric that stopped meaning what everyone pretended it meant.
The two numbers, and why the industry preferred the wrong one
Private equity has long been judged primarily on internal rate of return, IRR, a percentage that sounds like a verdict on performance. IRR has a convenient property for the people reporting it: it can be calculated from the estimated current value of the companies a fund still owns. Those estimates are marks, the fund's own judgment of what its portfolio is worth, and a fund can report a strong IRR without having sold anything or returned a dollar, because the number rests on what the assets are said to be worth, not on cash that changed hands.
The other number is DPI, distributed to paid-in capital, and it is brutally simple: of the money you gave the fund, how much has it actually given back. DPI cannot be marked, estimated, or narrated. It is cash in your account or it is not.
For most of the last decade the industry led with IRR, and it looked wonderful. The problem is that the two numbers have now diverged so far that the gap is the story. Distribution yields, the share of a fund's value actually returned to investors each year, have collapsed to about 11% over the last three years from more than 25% a decade ago. Investors are getting back less than half the cash, per year, that they used to, even as the reported returns stayed respectable.
The head of private equity funds at the Teacher Retirement System of Texas put the model failure plainly: no one's model expected nine-year holds or 10% distribution yields, and all their models are now telling them to commit less in 2026 than they planned a year ago. That is the sound of the metric substitution happening in real time: sophisticated investors deciding that the impressive percentage does not matter if the cash does not come.
Why the cash stopped coming
The mechanism is straightforward once the incentives are laid out. A private equity fund makes money for its investors by buying companies, improving them, and selling them, and the selling is the part that has frozen.
The industry is sitting on roughly $3.7 trillion in unsold assets, about 31,000 companies awaiting an exit. For every company sold in 2025, firms bought roughly three new ones, a decade-high imbalance, and the average holding period has stretched toward seven years from a historical norm closer to five and a half. Higher interest rates made the debt-fueled buyout math harder, a slow IPO market closed one exit door, and buyers and sellers could not agree on prices, in part because sellers did not want to sell below the optimistic marks their IRR depended on.
That last point is the trap closing on itself. The generous marks that flattered IRR became a reason not to sell, because selling at the real price would reveal the mark was too high and crater the reported return. So the paper valuation that made the fund look good became the thing preventing it from returning cash, and the fund drifts toward zombie status while still, notably, collecting fees.
The fee detail that makes it worse
This is the part that most sharpens the conflict of interest. A zombie fund is no longer making new investments but the manager continues to collect management fees on assets that may have been held for ten, twelve, or fifteen years.
Sit with the incentive that creates. The manager is paid to hold, not only to succeed. A fund that cannot sell its companies is a fund that keeps generating fees for the manager while returning little to the investors, which means the party deciding whether to keep waiting or take a lower price is the same party earning money from the waiting. That is not an accusation of bad faith so much as a description of misaligned incentives, and misaligned incentives do not require bad actors to produce bad outcomes. They just require everyone to follow the money in front of them.
The escape hatches, and why some investors distrust them
Faced with frozen exits, the industry engineered ways to manufacture liquidity, and they are worth understanding because they may relocate the problem rather than solve it.
Continuation funds are the most popular. A firm sells a company it already owns to a new fund it also manages, cashing out the investors who want out while keeping the asset. The value of assets in these vehicles rose from about $35 billion in 2019 toward $100 billion or more by the end of 2025. The mechanism is legitimate in principle and genuinely useful for good assets that need more time. The concern, voiced by investors including the Alaska Permanent Fund and the Teacher Retirement System of Texas, is that a firm selling a company to itself sets the price on both sides of the trade, which invites unrealistic valuations, and those worries intensified after companies like Wheel Pros and United Site Services went bankrupt following sales to continuation vehicles.
NAV loans are the other tool: a fund borrows against the value of its portfolio to pay distributions to investors. This delivers cash, and it does so by adding leverage against assets that are already struggling to sell, which returns money now by increasing risk later. Both techniques share a family resemblance. They convert a liquidity problem into a cash flow today and a question mark tomorrow, and whether that is prudent bridging or delaying the reckoning depends entirely on whether the underlying assets recover.
What it means beyond private equity
This matters past the funds themselves because of who the investors are. The limited partners trapped in these funds are pension systems, university endowments, and insurers, institutions with real obligations to retirees, students, and policyholders. When their capital is locked in aging funds returning 11% of value a year instead of 25%, the effects reach the pensioners and the university budgets that were counting on that money to recycle back and fund the next thing.
More than 40% of institutional limited partners carry exposure to zombie investments, which is why this is a structural issue rather than a few unlucky funds. And the pullback is already visible: investors are committing less new capital, which starves the next generation of funds and slows the whole machine, since PE depends on continuous recycling of returned capital into new commitments.
How this likely resolves
There is a plausible benign path. If interest rates decline and the economy avoids a downturn, exit markets can thaw, companies can be sold closer to their marks, cash can start flowing, and the zombie backlog can clear over several years. Some of these funds hold genuinely good businesses that simply need a better selling environment, and patience will be rewarded. That is the industry's base case, and it is not unreasonable.
The less benign path is that a meaningful share of these 31,000 companies were marked at prices the market will not pay, and the distributions never fully materialize, forcing writedowns that finally reconcile the paper returns with reality. The truth is almost certainly somewhere between, and which companies fall on which side is exactly what the current marks obscure.
Either way, the lasting change is the one in how these funds get judged. The industry spent a decade selling IRR, a number that could be engineered from optimistic marks. Its investors have now learned, expensively, to watch DPI instead, the cash that actually shows up. That shift in attention is more durable than any single fund's fate, because a performance measure that cannot be gamed changes the behavior of everyone being measured by it.