When rising land prices became loan collateral
The key to Japan’s late-1980s property boom was a feedback loop between land prices and credit. A bank considering a property loan cared not only about the borrower’s income, but also about the land offered as security. If that land appeared more valuable, it could support a larger loan. Buyers could then use borrowed money to bid more for property, pushing prices—and the apparent value of other properties—higher.
That logic made exceptionally expensive land seem less risky than it was. If prices kept climbing, a lender could expect the property to cover the debt even if the borrower could not repay from income. But the security depended on a price that the lending itself helped inflate. A high valuation was not cash in the bank; it was a promise that the land could later be sold for enough to repay the loan.
The reversal exposed the weakness
Once expectations changed and land prices began to fall, the same loop worked in reverse. Property securing a loan could be worth less than the debt it backed. Borrowers had less room to refinance or sell without taking a loss, while lenders faced weaker collateral and unpaid loans. Falling prices also discouraged buyers, putting further pressure on the market.
The striking lesson is that a boom can look financially sound while its collateral is rising. The risk is hidden in the assumption that yesterday’s higher price guarantees tomorrow’s repayment. When that assumption breaks, a valuable-looking asset can leave both borrower and bank short of what the loan requires.
