Two commercial buildings can look identical on the day you underwrite them. Both are one hundred percent leased. Both throw off the same net operating income. Both show the same clean rent roll. On every metric a quick review checks, they are twins. And one of them is carrying a risk the other is not, a risk that does not appear anywhere in the occupancy figure, because it is not about whether the space is leased today. It is about when those leases end.

In the first building, the leases expire in an orderly stagger, a manageable slice coming up each year. In the second, more than half the income is tied to leases that all expire inside the same eighteen-month window. When that window arrives, most of the building's income comes up for renewal or vacancy at once, and the owner faces a single, concentrated re-leasing event large enough to reshape the property's finances. The occupancy number said both buildings were full. It said nothing about the fact that one of them is about to have to re-lease itself half over, all at the same time.

This is lease expiry risk, sometimes called rollover risk, and it is one of the most consequential things about a commercial property that standard occupancy reporting completely hides.

Why Occupancy Is the Wrong Lens

Occupancy is a snapshot. It tells you what share of your space is leased at this instant, and that is genuinely useful, but it is silent on the two things that actually determine how durable your income is: how long the current leases run, and whether they end together or apart.

A property that is fully leased on stable, long, well-staggered terms has durable income. A property that is fully leased on terms that all roll in the same year has fragile income wearing the same one-hundred-percent-occupied costume. The occupancy figure cannot tell them apart, because occupancy measures the level of your income today and says nothing about its shape over time. For a finance leader, the shape is often the more important variable, and it is the one that gets ignored precisely because the headline number looks so reassuring.

The Metric That Reveals It

There is a standard metric built to expose exactly what occupancy hides. It is called weighted average lease expiry, or WALE (in the U.S. you will also hear weighted average lease term, WALT). It measures the average remaining lease term across the tenants in a property or portfolio, weighted by the income each tenant contributes, so that a large tenant's expiry counts for more than a small one's.

The reason it matters is that, as one commercial real estate reference explains, WALE speaks directly to income durability and even to value: properties with longer weighted average lease expiries are often perceived as less risky and can attract higher valuations and more favorable financing, and property managers use staggered lease expirations to minimize potential vacancies and income disruptions. A short WALE signals that a lot of your income is coming up for renegotiation soon. A long WALE signals that most of it is locked in for a while. The single number begins to describe the durability that occupancy leaves out.

But WALE has a trap of its own, and a finance leader has to see it. The average can look perfectly healthy while hiding a cliff. A portfolio with a comfortable five-year average WALE can still have a third of its income all expiring in year two, offset by some very long leases that pull the average up. The average is reassuring and the distribution is dangerous. So WALE is the start of the analysis, not the end. What you actually need to see is the full expiry ladder, how much income rolls in each individual year, because that is where a concentration hides.

What Happens When the Cliff Arrives

When a large share of income expires in a single window, the owner faces every re-leasing cost at once, magnified by concentration.

Some tenants will renew, but on renewal terms that are now up for negotiation, and if the market has softened since those leases were signed, they renew lower or not at all. Some tenants leave, and the space goes dark, carrying downtime while it sits vacant and then the full cost of re-leasing it: the tenant improvement dollars to fit it out for a new occupant, the leasing commissions to find them, the concessions and free rent to close the deal. Each of those is expensive for one lease. Hitting a large block of them simultaneously turns a manageable annual expense into a capital event.

And the timing risk is the cruelest part. You do not get to choose the market conditions on the day your cliff arrives. If your concentrated expiry lands in a soft leasing market, you are re-leasing a huge share of your building into weakness, from a position of need rather than strength, because the space is emptying whether you like the market or not. A well-staggered portfolio re-leases a small slice each year and averages across good markets and bad. A concentrated one bets a large share of its income on the conditions of a single moment it did not pick.

The Second and Third Hits: Value and Financing

Rollover risk does not stop at the operating statement. It follows the property into its valuation and its financing, which is why it belongs on a finance leader's radar rather than only a leasing team's.

A sophisticated buyer prices in your expiry profile. Two buildings with identical current NOI will not trade at identical prices if one has durable, staggered income and the other has a near-term cliff, because the buyer knows they are inheriting that cliff and the capital event attached to it. Concentrated near-term rollover is a discount at sale, and a long, well-distributed WALE is a premium, for the same reason lenders treat them differently: durable income supports better financing terms, and a big expiry cluster sitting near a loan's maturity is exactly the kind of risk that makes a lender cautious about refinancing. Stack a concentrated lease expiry on top of a debt maturity in the same year and you have combined two of the largest risks a property faces into a single moment, which is how an otherwise sound asset ends up in genuine trouble.

How Institutional Owners Actually Manage It

The largest and most sophisticated owners treat this as a standing discipline, not an occasional worry, and their public disclosures show exactly how. In its annual filing with the SEC, the institutional real estate owner Brookfield describes the risk plainly and its response even more plainly: it attempts to stagger the lease expiry profile so that it is not faced with disproportionate amounts of space expiring in any one year, keeping annual maturities to roughly a tenth of the portfolio, and further mitigates the risk by diversifying and by proactively leasing space in advance of contractual expiry.

Read what that actually contains, because it is the entire playbook in one sentence. Stagger the expiries so no single year carries a disproportionate share. Keep the annual rollover to a manageable slice rather than a cliff. Diversify so the risk is spread. And lease proactively, ahead of expiry, rather than waiting for the cliff to arrive and reacting to it. That is not exotic financial engineering. It is disciplined attention to the shape of the income over time, applied continuously, by owners who learned that occupancy today is not the same as safety tomorrow.

What a Finance Leader Should Do

Bringing that discipline down to a single portfolio comes to a few concrete practices. Measure the ladder, not just the average. Pull your expiry profile by year and look at how much income rolls in each one, rather than resting on a comfortable-looking WALE that might be masking a concentration. The year with the biggest slice is your risk, and you want to find it early.

Manage renewals as a portfolio, not one lease at a time. When you see a cluster forming, use lease structuring to break it up: stagger new terms and renewals deliberately so you are not signing everyone up to end in the same year, and start renewal conversations well ahead of expiry so a cliff becomes a series of manageable steps instead of one drop.

Watch the double concentrations. A single large tenant is one risk. A single expiry year is another. When they combine, one dominant tenant whose lease is also your biggest near-term expiry, or a big expiry cluster sitting in the same year your loan matures, the risks multiply rather than add. Those are the situations to identify years in advance, while there is still time to lease ahead, extend, or refinance around them.

The Honest Caveat: Longer Is Not Automatically Safer

It would be too simple to conclude that the goal is just to maximize lease length. It is not, and treating a long WALE as automatically good is its own mistake.

Long leases lock in today's rents, which is a benefit when the market is flat or falling and a liability when it is rising, because you have committed to below-market rents you cannot reset, the loss-to-lease problem in a different guise. And a long lease is only as durable as the tenant behind it, so a long WALE built on financially shaky tenants is a false comfort that can collapse the moment one of them defaults. The real objective is not maximum duration. It is a healthy shape: income spread across years so no single one dominates, anchored by tenants strong enough to actually honor the terms, at rents close enough to market that you are neither leaving money on the table nor exposed to a wave of departures. Durability and quality together, not length alone.

The Takeaway

A fully leased building can be a durable asset or a fragile one, and the occupancy figure that everyone leads with cannot tell you which. The difference lives in the timing of the leases, in whether the income is spread across the years ahead or bunched into a cliff you are walking toward without seeing it. That is why lease expiry risk is a finance leader's concern and not just a leasing metric: it shapes your NOI, your value, and your financing all at once, and it does so on a schedule that is already set the day you sign the leases.

The owners who manage it well are not the ones with the highest occupancy. They are the ones who look past occupancy to the shape of their income over time, who measure the expiry ladder rather than the reassuring average, and who spend the years before a cliff quietly flattening it into steps. Your building being full tells you where the income is today. It says nothing about whether it will still be there the year too many leases decide to end at once.

FAQ

1. What is lease expiry risk, or rollover risk?
It is the risk that a property will struggle to renew leases as they expire or to re-lease space that tenants vacate, and it becomes severe when many leases expire in the same window. A concentrated block of expiries forces the owner into a single large re-leasing event, exposing a big share of income to renewal negotiations, vacancy, and market conditions all at once.

2. Why doesn't occupancy show lease expiry risk?
Because occupancy is a snapshot of what is leased today, while rollover risk is about when those leases end. A building can be one hundred percent occupied with all its leases expiring in the same year, which is fragile, or fully occupied with well-staggered expiries, which is durable. Occupancy reports the level of income now and says nothing about its durability over time.

3. What is WALE and how is it used?
WALE, or weighted average lease expiry (also called WALT, weighted average lease term), measures the average remaining lease term across tenants, weighted by the income each contributes. A longer WALE generally signals more durable income and can support higher valuations and better financing, while a shorter WALE signals more near-term rollover. It is a starting point, but the full year-by-year expiry ladder matters more, because a healthy average can hide a concentrated cliff.

4. How do you reduce lease expiry risk?
By staggering lease expirations so no single year carries a disproportionate share of income, structuring new leases and renewals to spread out their end dates, and leasing proactively ahead of expiry rather than reacting to it. It also means avoiding dangerous concentrations, such as a single large tenant whose lease is also your biggest near-term expiry, or an expiry cluster sitting in the same year a loan matures.

5. Is a longer weighted average lease expiry always better?
No. A longer WALE improves income stability, but very long leases lock in current rents and can leave you below market in a rising-rent environment, and a long lease is only as reliable as the tenant behind it. The goal is a healthy shape, income spread across years, anchored by financially sound tenants, at rents reasonably close to market, rather than simply maximizing lease length.