Pinnacle West Capital Corporation and its subsidiary Arizona Public Service Company filed a combined Form 8-K on August 13, 2026, disclosing an underwriting agreement dated August 10, 2026, in connection with a debt offering totaling $700,000,000 in notes.

Key Highlights

  • Two-tranche offering: Arizona Public Service Company is issuing $100,000,000 of 5.50% Notes due 2035 and $600,000,000 of 6.25% Notes due 2056.
  • Underwriting agreement: The agreement is dated August 10, 2026, the date of the earliest event reported.
  • Indenture filings: A Ninth Supplemental Indenture (relating to the 5.50% Notes) and a Thirty-Fourth Supplemental Indenture (relating to the 6.25% Notes) are among the exhibits filed.
  • Registration statement: The offering is made pursuant to Registration Statement on Form S-3 (No. 333-277448 and No. 333-277448-01), which became effective on February 28, 2024.
  • Legal opinion: An opinion from Shirley A. Baum, Senior Vice President, General Counsel and Corporate Secretary, is included as Exhibit 5.1.
  • Signed by CFO: Andrew Cooper, Senior Vice President and Chief Financial Officer, signed on behalf of both registrants on August 13, 2026.

Arizona Public Service Prices $700M Dual-Tranche Notes Under 2024 Shelf Registration

According to the filing, Arizona Public Service Company entered into an underwriting agreement on August 10, 2026, in connection with an offering comprising two series of notes: $100,000,000 of 5.50% Notes due 2035 and $600,000,000 of 6.25% Notes due 2056. The combined offering totals $700,000,000 and is being conducted under the shelf registration statement (No. 333-277448 and No. 333-277448-01) that became effective on February 28, 2024.

The filing lists several exhibits supporting the transaction. The Ninth Supplemental Indenture, relating to the 5.50% Notes due 2035, was previously filed as Exhibit 4.1 to Arizona Public Service Company's Form 8-K dated August 22, 2005. The Thirty-Fourth Supplemental Indenture, relating to the $600,000,000 of 6.25% Notes due 2056, is filed as a new exhibit. Notes for each series, along with a legal opinion from the company's General Counsel, are also included among the exhibits.

The Form 8-K was filed jointly by Pinnacle West Capital Corporation (NYSE:PNW) and Arizona Public Service Company, each filing on its own behalf. The filing states that "each registrant is filing or furnishing on its own behalf all of the information contained in this Form 8-K that relates to such registrant." Andrew Cooper, Senior Vice President and Chief Financial Officer, executed the filing for both registrants on August 13, 2026.

What Was Disclosed

The 8-K discloses an underwriting agreement and supporting indenture documents for a two-tranche debt offering by Arizona Public Service Company totaling $700,000,000, consisting of 5.50% Notes due 2035 and 6.25% Notes due 2056.