Editor's note: This brief was summarised by The Property AI Newsroom from a report by Mortgage Strategy. Read the original article for full details.

Santander UK Mortgage Book Rises £35.7bn After TSB Acquisition

Santander UK has reported a significant increase in its mortgage book following the completion of its acquisition of TSB. The lender’s mortgage balances rose to £204.7 billion at the half-year results to the end of June, up from £169 billion at the end of 2025, representing a rise of £35.7 billion.

The acquisition has positioned Santander as the UK’s fourth-largest mortgage lender. Gross mortgage lending also increased to £14.7 billion in the first half of 2026, compared with £10.6 billion a year earlier. The integration of TSB was completed on 30 April.

Santander now serves four million additional customers and has become the UK’s third-largest provider of personal current accounts. The bank stated that it expects net lending growth to continue throughout 2026. It also forecasts that its banking net interest margin will remain stable and anticipates further cost efficiencies as it continues to integrate TSB and simplify its operations.

According to Santander, asset quality across its mortgage portfolio remained strong, with mortgage arrears staying low during the period. The Stage 3 loan ratio fell to 0.85%, partly due to a previously-completed sale of higher-risk mortgage assets. Customer deposits increased to £227.2 billion, largely attributed to the TSB acquisition and ongoing demand for fixed-term savings products, which the bank says supports mortgage lending.

Santander’s pre-tax profit fell 31% year-on-year to £528 million, mainly due to payouts for historical motor finance commission claims and restructuring costs. The bank reported that underlying lending activity remained resilient.

These developments may be of interest to UK letting agents and inventory clerks monitoring changes in the mortgage market and lender activity.