Cap Rate

Ask an appraiser what a building is “worth” and, eventually, the conversation collapses into one ratio: the capitalization rate, or cap rate. Divide the building’s annual net operating income by its price, and you get a percentage — 4%, 7%, 11% — that sounds like a bank deposit’s interest rate but behaves nothing like one.

The formula is almost insultingly simple. Cap rate = NOI ÷ price. A building earning $200,000 a year, bought for $4,000,000, has a 5% cap rate. Bought for $2,000,000 instead, the same income yields a 10% cap rate. The counterintuitive part — the part that trips up almost everyone the first time — is that the lower number usually marks the better building. A 3% cap rate on a landmark office tower in Tokyo signals overwhelming confidence; an 11% cap rate on a half-empty strip mall in a shrinking town signals the opposite. The market isn’t pricing what the asset earns this year. It’s pricing what it believes the asset will keep earning for years after that.

This is why cap rate is best understood not as a yield but as a trust index, inverted. Every dollar of income gets multiplied by however much faith buyers have in its durability. Rents likely to rise, tenants unlikely to leave, a neighborhood on the way up — all of that compresses into a lower cap rate, because buyers are willing to pay more for the same dollar of income today. Doubt about any of those things — an anchor tenant’s lease expiring soon, a market drowning in new supply, a neighborhood in decline — inflates the cap rate, because buyers demand a bigger discount to compensate for the risk that the income won’t last.

Cap rates also move with the broader cost of money. When interest rates rise, the return investors can get from a risk-free government bond rises too, and real estate — which carries real risk — has to offer a visibly higher return to stay competitive. That’s why cap rates across almost every asset class widened between 2022 and 2024, even though the buildings themselves hadn’t gotten worse: the alternative got more attractive, so the price of real estate had to adjust downward to keep the math working. This process even has its own name in the industry — cap rate decompression — and it’s one of the most reliable ways to explain why prices fall even when rents are flat or rising.

Where investors get into trouble is treating a high cap rate as a bargain by default. Sometimes it is: if a building looks cheap because the market is nervous about something you have a real plan to fix — a vacant floor you’re confident you can re-lease, a mediocre management team you’re about to replace — then a high cap rate is exactly the discount you want to buy into. But sometimes a high cap rate simply means the building is old, badly located, and structurally in decline, in which case it isn’t cheap at all — it’s expensive even after the discount, because the income stream itself is eroding.

The reverse trap matters just as much. A low cap rate on a supposedly “safe” trophy asset is not a guarantee of anything. It’s a bet that the consensus story about that building’s future will keep holding. When that consensus breaks — as it did across large swaths of the global office market once remote work became permanent rather than temporary — the buyers who paid the lowest cap rates for the appearance of safety are usually the ones who take the biggest write-downs, because they had left themselves no margin for being wrong.

Use cap rate the way a doctor uses a single vital sign: useful, fast, and never sufficient on its own. It tells you what the market currently believes. It never tells you whether the market is right.