National Grid has reported a sharp rise in first-half profit alongside record investment in its electricity and gas networks, as the FTSE 100 utility steps up spending to expand capacity in the UK and the north-eastern United States.

The group said statutory profit before tax more than doubled to £1.73 billion in the six months to 30 September, up from £826 million in the same period a year earlier. Statutory operating profit rose 55% to £2.36 billion, while revenue increased to £8.14 billion from £7.07 billion.

On the underlying measure the company uses to track continuing performance, operating profit rose 13% to £2.59 billion and underlying earnings per share increased 22% to 36.5p. Statutory earnings per share were 26.9p, up from 12.6p a year earlier.

National Grid was careful to explain the gap between the two profit measures. It said the statutory figures benefited from favourable timing swings worth £240 million compared with a year earlier, together with exceptional items including revaluation gains in its National Grid Partners portfolio and the non-recurring impact of divestments, worth £333 million year on year. The underlying figures strip out those effects to give a clearer view of trading.

Capital investment reached a record £6.71 billion in the half year, up by about a third on the £5.05 billion spent a year earlier. Most of the increase went into UK electricity transmission, where the company is working to double network capacity and cut the system constraint costs that arise when power cannot be moved to where it is needed.

UK electricity transmission was the main driver of earnings growth. Its underlying operating profit rose 45% to £1.23 billion, while its statutory operating profit increased 42% to £1.15 billion. The company said the first year of the new RIIO-T3 price control, which sets the revenue its regulated UK networks are allowed to earn, lifted earnings, alongside continued growth in its US rate base.

During the period National Grid enabled 2.5 gigawatts of new connections to be energised, bringing fresh generation and storage capacity onto the network. That included a 350-megawatt battery storage system at Uskmouth in Wales and the 1.4-gigawatt Sofia offshore wind farm. It also completed tunnelling work on two major projects, a 2.2-kilometre tunnel under the River Thames and a 3.4-kilometre tunnel under the Dwyryd Estuary.

The group raised its outlook for the full year. It now expects underlying earnings per share to grow by 15% to 16% in 2026/27 from the 78.0p baseline recorded in 2025/26, up from previous guidance of 13% to 15%. It plans to invest about £13.5 billion in the current financial year as part of a programme of at least £70 billion over five years to 2030/31.

Chief executive Zoe Yujnovich said capital investment was accelerating, major projects were progressing, and changes inside the company were sharpening performance for customers and stakeholders. She said the first-half progress strengthened confidence in delivering the five-year framework set out in March, including £40 billion of planned investment in the UK, which the company says will support more than 60,000 jobs.

National Grid also announced a $1.75 billion investment in Joulent, a business developing contracted power solutions for large-load customers in the United States. In New York, it began building the electricity connection for Micron's first semiconductor fabrication plant in the state, supporting 480 megawatts of demand, with a second plant planned to take the two facilities to more than one gigawatt.

Shareholders will receive an interim dividend of 16.97p per share, up from 16.35p a year earlier, in line with the company's policy of growing the dividend broadly in line with UK consumer price inflation including housing costs. National Grid said it recruited more than 3,600 new employees during the half year as its investment programme expanded.

Shares in National Grid rose 2.2% to 1,292.50p on Thursday morning in London after the results were published. The test for investors now is whether the group can sustain that pace of spending and convert it into regulated earnings without the balance sheet strain that comes with a programme of this size.