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Using Investment Portfolios to Secure Large Mortgage Loans
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How lenders use investment portfolios as security for high-value borrowing, and how to structure these deals for the best outcomes
For borrowers seeking multi-million-pound mortgage facilities, traditional lending based solely on income may not provide the flexibility or scale required. In these cases, an investment portfolio — whether comprising equities, bonds, or other marketable securities — can be a powerful tool in securing competitive terms.
In 2025, lenders are increasingly open to using investment portfolios as collateral, particularly in the private banking sector. This approach, sometimes referred to as a Lombard loan or portfolio-backed lending, allows borrowers to leverage their assets without liquidating them, preserving investment strategies while accessing significant property finance. Understanding how these arrangements work, and how to structure them correctly, is essential to making them a success.
How Portfolio-Backed Lending Works
Portfolio-backed lending is essentially a secured loan, where the investment portfolio serves as collateral alongside, or instead of, the property being purchased. The lender takes a legal charge over the portfolio, meaning they can liquidate assets if the loan is not repaid.
This arrangement can appeal to high-value borrowers because it allows them to:
- Preserve long-term investment positions without triggering capital gains tax.
- Access higher loan-to-value ratios than might be possible based on income alone.
- Negotiate more flexible repayment structures, including interest-only terms.
Private banks are the main providers of these facilities, tailoring the lending terms to the portfolio’s size, asset mix, and volatility. Our blog on How Private Banks Are Underwriting Mortgages in 2025 Using Investment Portfolios & Asset-Based Lending explores the broader context of this lending strategy.
The Advantages for Large Loan Borrowers
For clients seeking £2M–£10M+ mortgage loans, using an investment portfolio as collateral can open doors that would otherwise remain closed. Lenders may be willing to extend higher amounts, offer preferential interest rates, or provide bespoke repayment schedules aligned with the client’s liquidity events.
A well-structured portfolio-backed arrangement can also simplify the approval process. Rather than focusing heavily on detailed income analysis, the lender’s primary concern becomes the quality and stability of the portfolio. This is particularly useful for clients whose income is irregular or derived from sources such as dividends, bonuses, or offshore investments — scenarios that can challenge traditional affordability models.
Key Considerations and Risks
While portfolio-backed lending can be highly effective, it is not without its complexities. Market volatility can impact the value of the collateral, potentially triggering margin calls if the portfolio’s value falls below agreed thresholds. Lenders will typically require the portfolio to maintain a certain value relative to the loan amount, and may demand additional funds or securities if that ratio is breached.
Borrowers also need to consider the impact of granting a lender control over part of their investment portfolio. In some cases, the lender may impose restrictions on investment strategies or asset types while the portfolio is pledged. For these reasons, close coordination between your mortgage broker, wealth manager, and legal advisers is essential.
For clients using offshore investment portfolios, additional due diligence is required. We explore these issues in more depth in How to Finance UK Property with Offshore Income or Assets in 2025.
When This Strategy Works Best
Portfolio-backed lending is most effective for borrowers who:
- Have significant, diversified investment portfolios.
- Prefer not to liquidate assets to fund a property purchase.
- Require large or ultra-large mortgage facilities.
- Have complex or irregular income patterns.
It is particularly suited to buyers of prime property, where the purchase price exceeds the comfort level of mainstream lenders. For examples of structuring finance in this market, see our blog on Large Mortgage Loans in 2025: How to Secure £2M–£10M Finance.
Learn How Securities-Backed Lending Can Unlock Larger Property Finance Facilities
As this guide explains, using an investment portfolio as collateral can allow high-net-worth borrowers to secure substantial property finance without disrupting long-term investment strategies. The right structure can preserve liquidity, improve borrowing flexibility and unlock opportunities that traditional income-based lending may not support.
Our comprehensive Securities-Backed Lending Hub explores how private banks assess investment portfolios, how Lombard lending works, the impact of portfolio diversification and margin calls, and the strategies sophisticated borrowers use to finance high-value property purchases while keeping their investments intact.
Explore Our Securities-Backed Lending HubFrequently Asked Questions
Can I use my investment portfolio to secure a larger mortgage?
Yes. Many private banks and specialist lenders allow eligible investment portfolios to be used as additional collateral for a mortgage. By taking security over assets such as listed shares, bonds, ETFs or managed investment portfolios, lenders may be able to offer higher borrowing levels than would be possible based on income alone.
Do I have to sell my investments to use them as security?
No. One of the key advantages of portfolio-backed lending is that you normally retain ownership of your investments. Rather than selling assets and potentially triggering Capital Gains Tax or disrupting your investment strategy, the portfolio is pledged as collateral while remaining invested.
What types of investment assets can be used as collateral?
This depends on the lender, but commonly accepted assets include listed equities, government and corporate bonds, investment funds, ETFs, discretionary managed portfolios and cash deposits. Highly concentrated or illiquid investments may not be acceptable or may attract lower lending values.
How much can I borrow against my investment portfolio?
The amount available depends on the quality, diversification and volatility of the portfolio. Most lenders apply a loan-to-value (LTV) against the investment portfolio, typically ranging from 50% to 70%, although this varies depending on the underlying assets and the lender's appetite.
Can portfolio-backed lending help if I have irregular income?
Yes. This is one of the main reasons high-net-worth borrowers choose this approach. Business owners, entrepreneurs, investors and individuals with dividend income or overseas earnings often find that private banks place greater emphasis on overall wealth and asset quality than traditional affordability calculations.
What is the difference between a mortgage secured by investments and a Lombard loan?
A portfolio-backed mortgage uses your investment portfolio to strengthen or support a property mortgage. A Lombard loan is a separate lending facility secured solely against investments, allowing you to release liquidity without involving property as security. In some circumstances, the two can be used together as part of a wider financing strategy.
What happens if the value of my investment portfolio falls?
If the value of the pledged investments drops significantly, the lender may issue a margin call. This could require you to provide additional assets, reduce the borrowing, or pledge further security to maintain the agreed lending ratio. Understanding this risk is an important part of structuring the facility correctly.
Can offshore investment portfolios be used to support UK property finance?
Potentially, yes. Many private banks are experienced in working with internationally held investment portfolios. However, additional due diligence, jurisdictional checks and regulatory requirements may apply depending on where the assets are held and the borrower's tax residency.
Are private banks the main providers of portfolio-backed mortgages?
Yes. While some specialist lenders may consider these arrangements, private banks remain the primary providers. They are generally better equipped to assess complex wealth structures and can often offer bespoke lending solutions that are unavailable through mainstream lenders.
Who is portfolio-backed mortgage lending most suitable for?
This type of lending is typically suited to high-net-worth individuals, entrepreneurs, company directors, family offices and professional investors who hold substantial investment portfolios and require larger mortgage facilities without disrupting their long-term investment strategy.
Considering a Mortgage Supported by Your Investment Portfolio?
If you're looking to secure a £2 million to £10 million+ mortgage and want to explore how your investment portfolio could strengthen your borrowing position, Willow Private Finance can advise on specialist private bank and portfolio-backed lending solutions tailored to your circumstances. Contact us to discuss your requirements in confidence.
About the Author: Wesley Ranger
This article was written by Wesley Ranger, Director at Willow Private Finance. Wesley leads our team of specialist brokers, supporting clients in the UK and internationally. Over his career, he has arranged complex and high-value property finance transactions ranging from bespoke residential mortgages in the hundreds of thousands to structured facilities exceeding £100 million for major developments.
Operating within an FCA-regulated, whole-of-market brokerage, Wesley works closely with clients to design tailored strategies that align with their broader financial goals. His experience spans private banks, specialist lenders, and international financing structures, giving clients a competitive advantage in even the most challenging lending environments.
Important Notice
Your home or property may be repossessed if you do not keep up repayments on your mortgage. Borrowing secured against investment portfolios involves additional risks, including market volatility and potential margin calls. You should seek independent legal, tax, and investment advice before proceeding.
