UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 6-K

REPORT OF FOREIGN ISSUER

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

OF THE SECURITIES EXCHANGE ACT OF 1934

For the month of May 2021

(Commission File No. 001-39308)

CALLIDITAS THERAPEUTICS AB

(Translation of registrant’s name into English)

Kungsbron 1, C8
SE-111 22
Stockholm, Sweden
(Address of registrant’s 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): ¨

Company Announcement and Interim Report

On May 18, 2021, the Company announced its unaudited results for the three months ended March 31, 2021, which are further described in the Company’s Interim Report January 1 – March 31, 2021, copies of which are attached hereto as Exhibits 99.1 and 99.2, respectively, and are incorporated by reference herein.

EXHIBIT INDEX

Exhibit	Description
99.1	Company Announcement dated May 18, 2021
99.2	Interim Report – January 1 – March 31, 2021

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.

	CALLIDITAS THERAPEUTICS AB
Date: May 18, 2021	By:	/s/ Fredrik Johansson
		Fredrik Johansson
		Chief Financial Officer