An explainer from Watson AM, Basel
A personal guarantee is a binding commitment by an individual, usually the sponsor behind the borrowing company, to answer personally for the loan if the borrower does not repay. It is the second layer in most well-built property loans, sitting behind the registered mortgage, and it is the layer most often misunderstood: prized by lenders for reasons that have as much to do with behaviour as with recovery, and dismissed by sceptics who have seen guarantees fail. Both views hold a piece of the truth. Here is how the instrument works, what it adds to a loan that already carries a first-rank mortgage, and what separates a guarantee that pays from one that was never worth taking.
Why a mortgaged loan still wants a guarantee
Property loans are rarely made to people. They are made to companies, often a project company created to hold a single asset, so that the development's risks and contracts sit in one clean box. The structure is sensible and standard, and it has one consequence a lender must deal with: if the project fails, the company holding it may own nothing but the failed project. The mortgage reaches the property. Nothing else in the box is worth reaching.
The personal guarantee reaches past the box. It makes the individual who controls the project answerable for the debt from their own assets, and that does two different jobs at once.
The first job is recovery. Collateral covers what the property fetches at sale; the guarantee covers the gap the collateral can leave. A build that runs over budget, a sale that lands below the last valuation, an asset that took longer to realise than the interest it accrued: in each case the shortfall has an address, and the address is the sponsor.
The second job is quieter and, in practice, often more valuable: alignment. A sponsor who is personally answerable for the debt manages the project like their own money is at stake, because it is. Budgets get defended, problems get reported early, and the temptation to walk away from a difficult project loses its economics. A lender reads a willingly signed guarantee as information: the sponsor believes the plan enough to stand behind it personally. A sponsor who refuses one is also providing information.
Form matters as much as substance
Guarantees are contracts, and the law polices them closely because they are dangerous documents for the person signing. The details differ by jurisdiction; two distinctions matter almost everywhere.
The first is how independent the promise is. Some instruments are accessory, standing and falling with the underlying loan, while others are independent undertakings enforceable on their own terms. Swiss law draws this line sharply: the suretyship under articles 492 and following of the Code of Obligations is accessory and heavily formalised, while the guarantee under article 111 is independent of the underlying obligation. The formalities are the point, especially for individuals: a Swiss suretyship by a natural person above CHF 2'000 requires a public deed, and a married guarantor generally needs the spouse's written consent. A guarantee taken in the wrong form, or without the required consents, can be unenforceable precisely when it is needed.
The second is when the lender can call it. Under a guarantee of payment, or a first-demand guarantee, the lender can claim against the guarantor as soon as the borrower defaults. Under a guarantee of collection, the lender must first exhaust its remedies against the borrower and can claim only the shortfall. The distance between those two positions, measured in years of enforcement, is why loan documents define events of default carefully and say in terms which kind of guarantee is being given.
What the guarantee protects against, and where it fails
A guarantee fails in predictable ways, and each failure points to the diligence that prevents it. It fails when the form was wrong for the jurisdiction, which is a legal-review problem. It fails when the guarantor's wealth is thin, illiquid, already pledged to other lenders, or sitting in structures a claim cannot reach, which is an underwriting problem. And it weakens with time, because a guarantor's balance sheet on the day of default is what matters, and balance sheets move.
The discipline that answers all three is the same: underwrite the guarantor like a second borrower. A guarantee is only as strong as the balance sheet behind it, so the balance sheet is part of the file: verified, documented, and weighed at the same table as the property valuation. A guarantee accepted on a handshake and a reputation is decoration.
Where the guarantee sits in Watson AM's pipeline
In Watson AM's published nine-step due-diligence process, the guarantee runs through three stages. The financial and collateral review at step four covers the guarantor's standing alongside the project's numbers. Step five, security package design and verification, sets what the package contains and confirms each piece is properly constituted, with Swiss and local law firms checking the form rules of the jurisdiction at hand. Registration at step six then fixes the mortgage layer before any funds move.
- First-rank mortgageFirst claim on the property, registered before disbursement.
- Personal guaranteeThe sponsor answers personally for the debt; underwritten like a second borrower.
- Bank guaranteeThe layer that varies by deal; present where the deal documents confirm it.
Every one of the twelve published Watson AM case files is secured by a first-rank mortgage and a personal guarantee, from a CHF 1'000'000 Danish acquisition to the CHF 34'200'000 Norwegian hotel portfolio. Bank guarantees are the layer that varies, confirmed deal by deal from the documents.
Where Watson AM fits
Watson AM deploys investor and lending-partner capital into short- to mid-term, real-estate-backed projects across eleven European markets, and the pairing described in this piece, a registered first-rank mortgage plus a personal guarantee, is the constant across the firm's published book. The pairing is deliberate: the mortgage is the claim that can be verified in a register, the guarantee is the commitment that keeps the sponsor at the table, and the diligence pipeline exists to make sure both are real before a franc is disbursed.
For a professional investor comparing secured lending structures, the questions this article suggests are the ones we would ask of anyone: what form does the guarantee take, when can it be called, and who verified the wealth behind it. Investor and borrower material is available on request.
Common questions
What is a personal guarantee in property finance?
A personal guarantee is a binding commitment by an individual, usually the sponsor behind the borrowing company, to answer personally for the loan if the borrower does not repay. It sits alongside the mortgage: the mortgage secures the property, the guarantee reaches the person who controls the project.
Why take a personal guarantee if the loan already has a first-rank mortgage?
The mortgage only covers what the property fetches at sale. A guarantee covers the gap the collateral can leave: cost overruns, a value shortfall, or losses the asset cannot absorb. It also aligns incentives, because a sponsor who is personally answerable for the debt manages the project like their own money is at stake, which it is.
What makes a personal guarantee enforceable?
Form and substance. The form must match the local law: Swiss law, for example, distinguishes the accessory suretyship, which for individuals requires a public deed above CHF 2'000 and the spouse's consent for married guarantors, from the independent guarantee under article 111 of the Code of Obligations. The substance is the guarantor's verified wealth: a guarantee is only as strong as the balance sheet behind it, so serious diligence underwrites the guarantor like a second borrower.
Does a personal guarantee remove the risk from a loan?
No. It reduces the loss a lender expects to take if a default happens and it changes the borrower's incentives before one does, but no security instrument removes risk from lending. The guarantee is one layer in a package whose other layers, the registered mortgage and the diligence process, carry the rest of the weight.
Watson AM, Basel. This article is general market commentary for professional and qualified investors and for real-estate developers. It isn't investment, legal, or tax advice, or an offer of any financial product.
Sources
- Swiss Code of Obligations, art. 111 (independent guarantee) and arts. 492 to 512 (suretyship, including the public-deed and spousal-consent requirements for natural persons), via Fedlex, status as of 2025.
- CMS Expert Guide on Taking Security, Switzerland chapter, on the distinction between suretyship and independent guarantee under Swiss law, accessed July 2026.
- Walder Wyss, International Bank and Other Guarantees Handbook, Switzerland chapter, on form requirements and enforceability of Swiss guarantees and suretyships, accessed July 2026.
- DLA Piper, Giving and taking guarantees and security (global debt finance guide), on guarantees of payment versus guarantees of collection and typical events of default, accessed July 2026.