QuickLinks -- Click here to rapidly navigate through this document

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

FORM 6-K

Report of Foreign Private Issuer
Pursuant to Rule 13a-16 or 15d-16 of
the Securities Exchange Act of 1934

For the month of December 2003

Preem Holdings AB (publ)
(Translation of registrant's name into English)

Sandhamnsgatan 51,
S-11590,
Stockholm,
Sweden
(Address of principal executive offices)

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: ý Form 40-F: o

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): o

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): o

Indicate by check mark whether the registrant by furnishing the information contained in this Form is also thereby furnishing the information to the Commission pursuant to Rule 12g3-2(b) under the Securities Exchange Act of 1934.

Yes: o No: ý

If "Yes" is marked, indicate below the file number assigned to the registrant in connection with Rule 12g3-2(b): 82-

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 authorized.

		PREEM HOLDINGS AB (PUBL)
Date: December 2, 2003		By:	/s/ PER HÖJGÅRD Name: Per Höjgård Title: Chief Financial Officer

Further to our Report on Form 6-K for the quarter ended September 30, 2003, filed with the U.S. Securities and Exchange Commission on November 28, 2003, we provide the following information.

Operating income(loss) Before Depreciation and Amortization (OIBDA), Change in Working Capital and Free Cash Flow

The table below shows our analysis of Operating Income Before Depreciation and Amortization (OIBDA), Change in Working Capital and Free Cash Flow, for the three months and nine months ended September 30, 2002 and 2003.

	Three months ended September 30,				Nine months ended September 30,
	2002		2003		2002		2003
	(in millions of SEK)
OIBDA
Refinery contribution	219		453		655		1,713
Refining margin, hedge	0		(91	)	—		(493	)

Contribution to Fixed Costs	219		362		655		1,220
Fixed costs, refining (excl. depreciation)	(131	)	(141	)	(372	)	(410	)
Inventories, Market-to-Market	(218	)	227		(171	)	414
Price effect Norm Position, Oil	521		(25	)	1,276		(221	)
Other major items
Currency effect	56		(10	)	(151	)	(100	)
Waste heat sales	4		5		35		46
Ticket sales	17		15		47		51
Port income	11		12		40		36
Trading result and other OIBDA, Supply&refining	(163	)	(25	)	(92	)	(23	)

OIBDA, Supply and refining	315		420		1,267		1,012
OIBDA, other
Swedish Market	64		64		163		145
International market	(7	)	—		1		—
Corporate Center—price effect Norm position, Currency	(31	)	(112	)	(493	)	(392	)
Corporate Center—exchange rate difference purchase/sales	16		66		18		139
Corporate Center—other OIBDA	(23	)	(20	)	(28	)	(68	)
Preem Holdings AB	(7	)	(8	)	(22	)	(21	)

OIBDA Preem Holdings	327		410		905		815
Decrease in Inventories	531		909		399		562
Decrease in Current Receivables	576		1,166		301		974
Increase (Decrease) in Liabilities	48		(827	)	(1,111	)	(862	)

Change in Working capital	1,155		1,248		(411	)	674
Capital Expenditures	(294	)	(298	)	(719	)	(525	)

Free Cash Flow	1,188		1,360		(225	)	964

QuickLinks

SIGNATURES

PREEM HOLDINGS AB PUBL 6-K