Leverage is the main reason property builds fortunes, and the main reason it destroys them. Both come from the same arithmetic.

The maths that seduces

Buy a property for 300,000 with 60,000 of your own money and an 240,000 mortgage. The property rises 10% to 330,000. Your equity goes from 60,000 to 90,000 — a 50% gain on your money from a 10% move.

Now run it backwards. The property falls 10% to 270,000. Your equity is 30,000. You have lost half your capital, and the mortgage is unchanged — debt does not share your losses.

Negative equity

Fall far enough and your equity goes below zero: the loan exceeds the property's value. Nothing dramatic happens immediately if you keep paying — but you are trapped. You cannot sell without finding the shortfall in cash, and you cannot remortgage. Leverage removes your options at precisely the moment you want them.

Why property leverage is different from margin

An honest point in property's favour: a residential mortgage generally has no margin call. If share prices fall, a leveraged broker account can be liquidated at the worst moment. If house prices fall, the bank does not usually ring you — as long as the payments arrive. That structural patience is genuinely valuable.

Which reveals what actually kills leveraged landlords: not price falls, but cash flow. A void period, a rate reset, a broken boiler and a special levy in the same quarter is what forces a distressed sale.

Sizing it sensibly

  • Stress-test the payment at a rate several points above today's, not at today's.
  • Assume some vacancy every year. Vacancy is not bad luck, it is a running cost.
  • Keep a cash reserve per property — not one buffer covering three flats.
  • Ask whether the deal works at all if the price simply never rises. If it needs appreciation to make sense, it is a speculation with a tenant attached.

Summary

Leverage does not create returns; it multiplies whatever return the asset produces, including negative ones. Borrow an amount you could keep servicing through a bad year, and the sword only has one edge pointed at you.