Included in the statement of financial position are certain financial assets and liabilities which are measured at fair value. The following table categorises these assets and liabilities by the valuation methodology applied in determining their fair value using the fair value hierarchy described on page 203 of the Annual Report and Accounts for the year ended 31 March 2026.


	30 September 2026				31 March 2026
	Level 1 £m	Level 2 £m	Level 3 £m	Total £m	Level 1 £m	Level 2 £m	Level 3 £m	Total £m
Assets
Investments held at fair value through profit and loss	2,341	—	1,637	3,978	1,914	—	450	2,364
Investments held at fair value through other comprehensive income1	—	374	—	374	—	385	—	385
Financing derivatives	—	551	21	572	—	691	26	717
Commodity contract derivatives	—	134	14	148	—	111	10	121
	2,341	1,059	1,672	5,072	1,914	1,187	486	3,587
Liabilities
Financing derivatives	—	(1,231)	(41)	(1,272)	—	(864)	(86)	(950)
Commodity contract derivatives	—	(90)	(23)	(113)	—	(55)	(13)	(68)
	—	(1,321)	(64)	(1,385)	—	(919)	(99)	(1,018)
Total	2,341	(262)	1,608	3,687	1,914	268	387	2,569

Our Level 2 financial investments held at fair value primarily include bonds with a tenor greater than one year and are valued using quoted prices for similar instruments in active markets, or quoted prices for identical or similar instruments in inactive markets. Alternatively, they are valued using models where all significant inputs are based directly or indirectly on observable market data.

Our Level 2 financing derivatives include cross-currency, interest rate and foreign exchange derivatives. We value these derivatives by discounting all future cash flows by externally sourced market yield curves at the reporting date, taking into account the credit quality of both parties. These derivatives can be priced using liquidly traded interest rate curves and foreign exchange rates, and therefore we classify our vanilla trades as Level 2 under the IFRS 13 framework.

Our Level 2 US commodity contract derivatives include over-the-counter gas and power swaps as well as forward physical gas deals. We value our contracts based on market data obtained from the New York Mercantile Exchange (NYMEX) and the Intercontinental Exchange (ICE), where monthly prices are available. We discount based on externally sourced market yield curves at the reporting date, taking into account the credit quality of both parties and liquidity in the market. Our commodity contracts can be priced using liquidly traded swaps. Therefore, we classify our vanilla trades as Level 2 under the IFRS 13 framework.

Our Level 3 US commodity contract derivatives primarily consist of our forward purchases of electricity and gas that we value using proprietary models. Derivatives are classified as Level 3 where significant inputs into the valuation technique are neither directly nor indirectly observable (including our own data, which are adjusted, if necessary, to reflect the assumptions market participants would use in the circumstances).

Our Level 3 investments include equity instruments accounted for at fair value through profit and loss. These equity holdings are part of our corporate venture capital portfolio held by National Grid Partners and comprise a series of relatively small, early-stage non-controlling minority interest unquoted investments where prices or valuation inputs are unobservable. Out of 42 equity investments, 27 are fair valued based on the latest transaction price (a price within the last 12 months), either being the price we paid for the investments, marked to a latest round of funding and adjusted for our preferential rights or based on an internal model. In addition, we have 15 investments with no transaction in the last 12 months which are fair valued using an internal valuation process. Between 12 and 18 months a blend between Black-Scholes Murton Option Pricing Model Backsolve and other techniques are utilised such as proxy group revenue multiples, discounted cash flow, comparable company analysis and probability weighted expected return approach in order to triangulate a valuation. After 18 months the valuation is based on these alternative methods as the last fundraising price or other observable market price is no longer a reliable basis for valuation.

Our Level 3 investments also include our investment in Sunrun Neptune 2016 LLC, which is accounted for at fair value through profit and loss. The investment is fair valued by discounting expected cash flows using a weighted average cost of capital specific to Sunrun Neptune 2016 LLC.

On 30 June 2026, the Group acquired an investment in Joulent LLC, a US-based technology-driven energy company that develops power solutions for large-load customers. The investment is measured at fair value through profit and loss in accordance with IFRS 9 and is classified within Level 3 of the fair value hierarchy due to the absence of observable market inputs. At 30 September 2026, the investment was recognised at £952 million ($1,263 million), comprising the initial consideration paid on acquisition together with capital contributions funded to date. Given the limited period between acquisition and the reporting date, and the absence of observable transactions or other market evidence subsequent to acquisition, management has concluded that the transaction price together with capital contributions funded represents the best evidence of fair value at 30 September 2026. Accordingly, no fair value gain or loss has been recognised since acquisition. The Group has also committed to provide further capital contributions of up to £366 million ($486 million) to support Joulent LLC’s capital investment programme and development activities as costs are incurred.

In addition, the Group entered into a 364-day funding facility with Joulent LLC during the period. The facility includes both interest and equity participation features and is therefore measured at fair value through profit and loss in accordance with IFRS 9. The facility loan receivable is classified within Level 3 of the fair value hierarchy as valuation requires the use of unobservable inputs. At 30 September 2026, £120 million ($159 million) had been drawn under the facility. Given the proximity of the loan receivable’s inception to the reporting date, we have concluded that its fair value is not materially different from its carrying value.


	Financing derivatives		Commodity contract derivatives		Other
Six months ended 30 September	2026	2025	2026	2025	2026	2025
	£m	£m	£m	£m	£m	£m
10% increase in commodity prices	—	—	20	3	—	—
10% decrease in commodity prices	—	—	(20)	(2)	—	—
+10% market area price change	—	—	13	1	—	—
-10% market area price change	—	—	(15)	(2)	—	—
+20 basis point increase in Limited Price Index (LPI) market curve	(12)	(32)	—	—	—	—
-20 basis point decrease in LPI market curve	12	30	—	—	—	—
+20 basis point increase between Retail Price Index (RPI) and Consumer Price Index (CPI)	24	29	—	—	—	—
-20 basis point decrease between RPI and CPI	(23)	(27)	—	—	—	—
+100 basis points change in discount rate	—	—	—	—	(6)	(6)
-100 basis points change in discount rate	—	—	—	—	7	7
+10% change in venture capital price	—	—	—	—	107	26
-10% change in venture capital price¹	—	—	—	—	(107)	(26)

The impacts disclosed above were considered on a contract by contract basis with the most significant unobservable inputs identified. A reasonably possible change in assumptions for other Level 3 assets and liabilities would not result in a material change in fair values.


	Financing derivatives		Commodity contract derivatives		Other1		Total
	2026	2025	2026	2025	2026	2025	2026	2025
	£m	£m	£m	£m	£m	£m	£m	£m
At 1 April	(60)	(64)	(3)	(20)	450	407	387	323
Net (losses)/gains through the consolidated income statement for the period2,3	(3)	3	(6)	72	197	(9)	188	66
Purchases	—	—	—	—	1,097	9	1,097	9
Settlements	43	—	—	(12)	(107)	(1)	(64)	(13)

At 30 September	(20)	(61)	(9)	40	1,637	406	1,608	385

3.Losses of £6 million (2025: gains of £72 million) are attributable to the commodity contract derivative financial instruments held at the end of the reporting period and have been recognised in other operating costs in the consolidated income statement.