TransAlta (NYSE: TAC) files 6-K with new underwriting agreement exhibit

Rhea-AI Filing Summary

TransAlta Corporation filed a Form 6-K as a foreign private issuer for December 2025, primarily to submit an Underwriting Agreement dated December 11, 2025 as Exhibit 99.1. This exhibit is incorporated by reference into TransAlta’s Form F-10 registration statement (File No. 333-292019), with the report signed by Corporate Secretary Kelly Galloway.

Form 6-K: How Foreign Companies Report to the SEC →

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 December 2025

Commission File Number: 001-15214

TransAlta Corporation

(Translation of registrant’s name into English)

Suite 1400, 1100 - 1st Street S.E., Calgary, Alberta, T2G 1B1

(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 ☐   Form 40-F ☒

INCORPORATION BY REFERENCE

Exhibit 99.1 of this Form 6-K is incorporated by reference as an additional exhibit to the registrant’s Registration Statement on Form F-10 (File No. 333-292019).

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.

						TransAlta Corporation
						(Registrant)
Date: December 15, 2025						/s/ Kelly Galloway
						Kelly Galloway
						Corporate Secretary

EXHIBIT INDEX

Exhibit Number		Description
99.1		Underwriting Agreement, dated December 11, 2025

FAQ

What does TransAlta Corporation (TAC) report in this December 2025 Form 6-K?

TransAlta uses this Form 6-K to submit an Underwriting Agreement dated December 11, 2025 as Exhibit 99.1. The filing also notes that this exhibit is incorporated by reference into TransAlta’s existing Form F-10 registration statement.

How is the Exhibit 99.1 underwriting agreement used by TransAlta (TAC)?

The Underwriting Agreement filed as Exhibit 99.1 is incorporated by reference into TransAlta’s Form F-10 registration statement, File No. 333-292019. This means the agreement becomes a formal part of that registration for regulatory and disclosure purposes.

Which registration statement does TransAlta’s Form 6-K reference?

The Form 6-K specifies that Exhibit 99.1 is incorporated by reference into TransAlta Corporation’s Form F-10 registration statement with File No. 333-292019. This linkage connects the newly filed underwriting agreement to the company’s existing securities registration.

Who signed TransAlta Corporation’s December 2025 Form 6-K?

The Form 6-K was signed on behalf of TransAlta Corporation by Corporate Secretary Kelly Galloway, dated December 15, 2025. This signature confirms the company’s authorization and certifies the submission of the underwriting agreement as an exhibit.

What exhibit is included with TransAlta (TAC) December 2025 Form 6-K?

The filing includes Exhibit 99.1, described as an Underwriting Agreement dated December 11, 2025. This agreement is formally added as an exhibit to the company’s Form F-10 registration statement through incorporation by reference.

Where is TransAlta Corporation’s principal executive office located?

TransAlta Corporation lists its principal executive office at Suite 1400, 1100 - 1st Street S.E., Calgary, Alberta, T2G 1B1. This address appears in the Form 6-K header as the company’s main corporate location for regulatory correspondence.