As per attachment

GlaxoSmithKline Pharmaceuticals Limited GSK House, Dr. Annie Besant Road, Worli, Mumbai - 400 030 Tel No: +91 22 2495 9595 Web: www.gsk-india.com Email: askus@gsk.com 25th September 2026 BSE LIMITED THE NATIONAL STOCK EXCHANGE OF INDIA LIMITED Phiroze Jeejeebhoy Towers Exchange Plaza, 5th Floor, Plot No. C/1, G Block Dalal Street Bandra-Kurla Complex, Bandra (East) Mumbai - 400001 Mumbai - 400051 Dear Sir, Sub: Closure of “Trading Window” We wish to inform you that in terms of the provisions of SEBI (Prohibition of Insider Trading) Regulations 2015, the trading period for buying or selling of Company's shares is closed from Thursday, 1st October 2026 till 48 hours after the announcement/declaration of the Un-audited Financial Results of the Company for the second quarter and half year ended 30th September 2026. The date of Board Meeting for declaration of the Un-Audited Financial Results of the Company for the second quarter and half year ended 30th September 2026 will be intimated in due course. Kindly take same on record. Thanking you, Yours faithfully For GlaxoSmithKline Pharmaceuticals Limited Ajay Nadkarni Vice President – Administration, Real Estate & Company Secretary CIN No. L24239MH1924PLC001151