Company: NEWEN
Filing Date: 2025-11-06
Form Type: 6-K
Source: 0001004315-25-000016
Chunk: 0

Company: NATIONAL GRID PLC
Filing Date: 2025-11-06
Form: 6-K
Chunk 0
---
### UNITED STATES

### SECURITIES AND EXCHANGE COMMISSION

#### Washington D.C. 20549

#### FORM 6-K

### REPORT OF FOREIGN PRIVATE ISSUER

#### PURSUANT TO RULE 13a-16 OR 15d-16

#### UNDER THE SECURITIES EXCHANGE ACT OF 1934

#### For the month of November 2025

#### Commission File Number: 001-14958

#### NATIONAL GRID plc
<div align='center'>(Translation of Registrant’s Name into English)</div>

#### 1-3 Strand

#### London WC2N 5EH, England
<div align='center'>(Address of principal Executive Office)</div>

Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F.
☒ Form 20-F ☐ Form 40-F

### INCORPORATION BY REFERENCE
This report and Exhibit 99.1 of this report on Form 6-K shall be deemed to be incorporated by reference into the registration statements on Form F-3 (Registration Numbers 333-281812 and 333-256888) and Form S-8 (Registration Numbers 333-184558, 333-170716, 333-175852, 333-155527, 333-149828, 333-107727, 333-103768, 333-97249, 333-65968, and 333-33094) of National Grid plc (the "Company") (including any prospectuses forming a part of such registration statements) and to be a part thereof from the date on which this report is filed, to the extent not superseded by documents or reports subsequently filed or furnished.

Please see Exhibit 99.1 Announcement sent to the London Stock Exchange on 6 November 2025 — 'National Grid 2025/26 Half Year Results Statement'

### SIGNATURE
Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

| NATIONAL GRID plc |     |                         |
| By:               |     | /s/Julian Baddeley      
 _______________________ |
|                   |     | Julian Baddeley         
 Company Secretary       |

Date: 6 November 2025

### EXHIBIT INDEX
| Exhibit 
 No.     |     | Description