BT confirmed its pension fund lost £300mn after writing off an 8.7% stake in Thames Water's parent company, Kemble Water. The write-off, made in 2024, marks the first public acknowledgment of losses from the utility investment as Thames Water struggles under its £20bn debt burden.

The £33.2bn BT pension scheme, which serves 213,000 retired employees and pays out £2.9bn annually in benefits, saw assets return £569mn less than expected last year. BT's pension deficit increased to £4.2bn from £4.1bn, prompting £800mn in deficit contributions during the last financial year.

Thames Water's financial crisis has drawn major creditors including Elliott Management and Apollo Global Management into negotiations with regulator Ofwat. The utility faces a cash crunch by October, with senior lenders holding the majority of its £20bn debt pile seeking formal ownership approval.

Political pressure mounts as UK environment secretary warns the creditor deal could burden consumers, while potential PM Andy Burnham supports renationalisation. The pension fund's Thames Water losses underscore risks in infrastructure investments amid the utility's ongoing restructuring.