Report of Foreign Issuer Pursuant to Rule 13a-16 or 15d-16 (6-k)

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 October 2020

Commission File Number 001-15170

GlaxoSmithKline plc

(Translation of registrant's name into English)

980 Great West Road, Brentford, Middlesex, TW8 9GS

(Address of principal executive office)

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 . . . .X. . . . Form 40-F . . . . . . . .

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(1): ____

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7): ____

TR-1: Standard form for notification of major holdings

NOTIFICATION OF MAJOR HOLDINGS (to be sent to the relevant issuer and to the FCA in Microsoft Word format if possible)

1a. Identity of the issuer or the underlying issuer of existing shares to which voting rights are attached:			GlaxoSmithKline PLC
1b. Please indicate if the issuer is a non-UK issuer (please mark with an "X" if appropriate)
Non-UK issuer
2. Reason for the notification (please mark the appropriate box or boxes with an "X")
An acquisition or disposal of voting rights						X
An acquisition or disposal of financial instruments
An event changing the breakdown of voting rights
Other (please specify):
3. Details of person subject to the notification obligation
Name			The Capital Group Companies, Inc.
City and country of registered office (if applicable)			Los Angeles, USA
4. Full name of shareholder(s) (if different from 3)
Name
City and country of registered office (if applicable)
5. Date on which the threshold was crossed or reached:			27/10/2020
6. Date on which issuer notified (DD/MM/YYYY):			29/10/2020
7. Total positions of person(s) subject to the notification obligation:
	% of voting rights attached to shares (total of 8.A)	% of voting rights through financial instruments (total of 8.B.1 + 8.B.2)		Total of both in % (8.A + 8.B)	Total number of voting rights of issuer
Resulting situation on the date on which threshold was crossed or reached	5.04%	0.00%		5.04%	5,017,375,238
Position of previous notification (if applicable)	4.99%	0.00%		4.99%

8. Notified details of the resulting situation on the date on which the threshold was crossed or reached:
A: Voting rights attached to shares
Class/type of shares ISIN code (if possible)	Number of voting rights				% of voting rights
	Direct (Art 9 of Directive 2004/109/EC) (DTR5.1)	Indirect (Art 10 of Directive 2004/109/EC) (DTR5.2.1)			Direct (Art 9 of Directive 2004/109/EC) (DTR5.1)	Indirect (Art 10 of Directive 2004/109/EC) (DTR5.2.1)
GB0009252882 Common Stock		207,532,584				4.14%
US37733W1053 Depository Receipt		45,497,838				0.91%

SUBTOTAL 8.A	253,030,422				5.04%

B 1: Financial Instruments according to Art. 13(1)(a) of Directive 2004/109/EC (DTR5.3.1.1 (a))
Type of financial instrument	Expiration date	Exercise/ Conversion Period	Number of voting rights that may be acquired if the instrument is exercised/converted			% of voting rights
N/A
		SUBTOTAL 8.B.1

B 2: Financial Instruments with similar economic effect according to Art. 13(1)(b) of Directive 2004/109/EC (DTR5.3.1.1 (b))
Type of financial instrument	Expiration date	Exercise/ Conversion Period	Physical or cash settlement	Number of voting rights		% of voting rights
N/A
			SUBTOTAL 8.B.2

9. Information in relation to the person subject to the notification obligation (please mark the applicable box with an "X")
Person subject to the notification obligation is not controlled by any natural person or legal entity and does not control any other undertaking(s) holding directly or indirectly an interest in the (underlying) issuer.
Full chain of controlled undertakings through which the voting rights and/or the financial instruments are effectively held starting with the ultimate controlling natural person or legal entity (please add additional rows as necessary)					X
Name	% of voting rights if it equals or is higher than the notifiable threshold		% of voting rights through financial instruments if it equals or is higher than the notifiable threshold	Total of both if it equals or is higher than the notifiable threshold
Capital Research and Management Company	5.02%			5.02%
Capital Bank and Trust Company
Capital International, Inc.
Capital International Sàrl
Capital International Limited
Total	5.04%			5.04%


10. In case of proxy voting, please identify:
Name of the proxy holder
The number and % of voting rights held
The date until which the voting rights will be held

11. Additional information:
The Capital Group Companies, Inc. ("CGC") is the parent company of Capital Research and Management Company ("CRMC") and Capital Bank & Trust Company ("CB&T"). CRMC is a U.S.-based investment management company that serves as investment manager to the American Funds family of mutual funds, other pooled investment vehicles, as well as individual and institutional clients. CRMC and its investment manager affiliates manage equity assets for various investment companies through three divisions, Capital Research Global Investors, Capital International Investors and Capital World Investors. CRMC is the parent company of Capital Group International, Inc. ("CGII"), which in turn is the parent company of four investment management companies ("CGII management companies"): Capital International, Inc., Capital International Limited, Capital International Sàrl and Capital International K.K. CGII management companies and CB&T primarily serve as investment managers to institutional and high net worth clients. CB&T is a U.S.-based investment management company that is a registered investment adviser and an affiliated federally chartered bank. Neither CGC nor any of its affiliates own shares of the Issuer for its own account. Rather, the shares reported on this Notification are owned by accounts under the discretionary investment management of one or more of the investment management companies described above.

Place of completion		Los Angeles
Date of completion		29/10/2020

SIGNATURES

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 authorised.

	GlaxoSmithKline plc
	(Registrant)

Date: October 30, 2020

	By:/s/ VICTORIA WHYTE --------------------------

	Victoria Whyte
	Authorised Signatory for and on
	behalf of GlaxoSmithKline plc