Applied Optoelectronics switches auditor to PwC

Applied Optoelectronics, Inc. has changed its independent auditor, dismissing Grant Thornton LLP and appointing PricewaterhouseCoopers LLP for the fiscal year ending December 31, 2026.

Filing Impact

(Moderate)

Filing Sentiment

(Neutral)

Form Type

8-K

Rhea-AI Filing Summary

Applied Optoelectronics, Inc. has changed its independent auditor, dismissing Grant Thornton LLP and appointing PricewaterhouseCoopers LLP for the fiscal year ending December 31, 2026. Grant Thornton will still review the company’s consolidated financial statements for the quarter ending March 31, 2026.

Grant Thornton’s audit reports for the years ended December 31, 2024 and 2025 contained no adverse opinions, disclaimers, or qualifications, and there were no disagreements or reportable events under Regulation S‑K. A previously disclosed material weakness in controls over review of technical accounting analysis was remediated as of December 31, 2025.

Insights

Auditor switch to PwC with clean prior opinions and remediated weakness.

Applied Optoelectronics is replacing Grant Thornton with PricewaterhouseCoopers LLP as independent auditor for the year ending December 31, 2026, after a competitive selection run by the Audit Committee. Grant Thornton remains engaged for the quarter ending March 31, 2026, which supports continuity through the current reporting cycle.

Grant Thornton’s reports for the years ended December 31, 2024 and 2025 had no adverse opinions or qualifications, and the company reports no disagreements or reportable events during that period. A material weakness in controls over review of technical accounting analysis, first disclosed for 2024, is described as remediated by December 31, 2025, suggesting improved control oversight.

The change to PwC mainly affects audit oversight rather than day‑to‑day operations. Subsequent annual and quarterly reports after the 2026 year-end will show how PwC’s audits address internal controls and financial reporting under its new engagement.

8-K Event Classification

2 items: 4.01, 9.01

2 items

Item 4.01 Changes in Registrant's Certifying Accountant Governance

The company changed its independent auditing firm, which may involve disagreements on accounting matters.

Item 9.01 Financial Statements and Exhibits Exhibits

Financial statements, pro forma financial information, or exhibit attachments filed with this report.

Key Figures

Auditor dismissal date: May 4, 2026 New auditor fiscal year: Year ending December 31, 2026 Quarter still reviewed by Grant Thornton: Quarter ending March 31, 2026 +1 more

4 metrics

Auditor dismissal date May 4, 2026 Audit Committee approved dismissal of Grant Thornton

New auditor fiscal year Year ending December 31, 2026 PwC engaged as independent auditor

Quarter still reviewed by Grant Thornton Quarter ending March 31, 2026 Existing engagement unaffected by dismissal

Material weakness remediated as of December 31, 2025 Controls over review of technical accounting analysis

Key Terms

independent registered public accounting firm, Audit Committee, material weakness, reportable events, +1 more

5 terms

independent registered public accounting firm financial

"to determine the Company’s independent registered public accounting firm for the fiscal year ending December 31, 2026"

An independent registered public accounting firm is an outside accounting company officially registered with the government regulator to examine and report on a public company's financial records and controls. Investors treat its reports like an impartial inspector’s certificate — they add credibility to financial statements, help spot errors or misleading claims, and reduce the risk that shareholders are relying on unchecked or biased numbers.

Audit Committee financial

"The Audit Committee (the “Committee”) of the Board of Directors"

A company's audit committee is a small group of board members who act like independent inspectors for the firm's finances, overseeing how financial reports are prepared, monitoring internal controls, and managing the relationship with external auditors. Investors care because a strong audit committee reduces the risk of accounting errors, fraud, or misleading statements, making financial statements more trustworthy and helping protect shareholder value.

material weakness financial

"except for the material weakness in the Company’s operation of controls"

A material weakness is a significant flaw in the systems and checks a company uses to ensure its financial reports are accurate, meaning errors or fraud could happen and not be caught. For investors it matters because it raises the risk that reported results are unreliable—similar to finding a hole in a ship’s hull—potentially leading to corrected financials, regulatory action, reduced trust, and negative effects on stock value and borrowing costs.

reportable events regulatory

"There were no “reportable events” (as that term is defined in Item 304(a)(1)(v)"

Reportable events are significant incidents or changes a company is legally required to disclose to regulators and the public, such as major safety problems, legal actions, financial irregularities, or management changes. They matter to investors because these events can alter a company’s risk profile or future performance, much like a dashboard warning light signals a problem that could affect a car’s safety or reliability. Timely disclosure helps investors make informed decisions and maintain market fairness.

Regulation S-K regulatory

"as defined in Item 304(a)(1)(iv) of Regulation S-K and the related instructions"

A set of U.S. Securities and Exchange Commission rules that tell public companies which narrative and qualitative details must be disclosed in filings, such as risk factors, management discussion, executive pay, legal proceedings and business description. Think of it as a standardized checklist or blueprint that ensures investors get the same types of background information from every company so they can compare risks, management quality and strategy before making investment decisions.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What did Applied Optoelectronics (AAOI) announce about its auditor?

Applied Optoelectronics is replacing Grant Thornton LLP with PricewaterhouseCoopers LLP as its independent auditor for 2026. The Audit Committee approved the dismissal of Grant Thornton and the appointment of PwC on May 4, 2026, following a competitive selection process involving multiple audit firms.

Why was Grant Thornton LLP dismissed by Applied Optoelectronics (AAOI)?

The company states Grant Thornton was dismissed after a competitive selection for the 2026 audit. The Audit Committee evaluated proposals from participating firms and then approved moving to PwC. The disclosure does not cite disagreements or reportable events as reasons for the change.

Were there any disagreements between Applied Optoelectronics (AAOI) and Grant Thornton?

The company reports no disagreements with Grant Thornton under Regulation S‑K definitions. For 2024, 2025, and through May 4, 2026, it cites no disputes about accounting principles, financial statement disclosure, or audit procedures that would have required mention in Grant Thornton’s audit reports.

Did Applied Optoelectronics (AAOI) have any material weaknesses in internal control?

The company previously disclosed a material weakness in controls over review of technical accounting analysis. This weakness was first reported for the year ended December 31, 2024, and is described as remediated as of December 31, 2025, indicating corrective actions were implemented by that date.

What role will PricewaterhouseCoopers LLP play for Applied Optoelectronics (AAOI)?

PwC has been appointed as the independent registered public accounting firm for the 2026 fiscal year. The firm will audit Applied Optoelectronics’ consolidated financial statements for the year ending December 31, 2026, replacing Grant Thornton in that role after completion of the March 31, 2026 quarterly review.

Did Applied Optoelectronics (AAOI) consult PwC before appointing it as auditor?

The company states it did not consult PwC on key accounting or audit matters before appointment. During 2024, 2025, and through May 4, 2026, there were no consultations on specific transactions, expected audit opinions, disagreements, or reportable events as described in Regulation S‑K.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Accepted by SEC EDGAR 05/08/2026 - 08:00 AM

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): May 4, 2026

Applied Optoelectronics, Inc.

(Exact name of registrant as specified in its charter)

Delaware	001-36083	76-0533927
(State of incorporation)	(Commission File Number)	(I.R.S. Employer Identification No.)

13139 Jess Pirtle Blvd.
Sugar Land, Texas 77478

(Address of principal executive offices and zip code)

(281) 295-1800

(Registrant’s telephone number, including area code)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

Title of each class	Trading Symbol(s)	Trading Name of each exchange on which registered
Common Stock, Par value $0.001	AAOI	NASDAQ Global Market

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company ¨

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. o

Item 4.01. Changes in Registrant’s Certifying Accountant.

(a) Dismissal of Independent Registered Public Accounting Firm

The Audit Committee (the “Committee”) of the Board of Directors of Applied Optoelectronics, Inc. (the “Company”) recently completed a competitive selection process, inclusive of the Company’s current independent registered public accounting firm, Grant Thornton LLP (“Grant Thornton”), to determine the Company’s independent registered public accounting firm for the fiscal year ending December 31, 2026. Following the review and evaluation of the proposals of the participating firms, on May 4, 2026, the Committee approved the dismissal of Grant Thornton as the Company’s independent registered public accounting firm. Grant Thronton was previously engaged to perform a review of the Company’s consolidated financial statements for the quarter ending March 31, 2026. The dismissal of Grant Thornton does not affect its engagement for the quarter ending March 31, 2026.

Grant Thornton’s reports on the Company’s consolidated financial statements as of and for the fiscal years ended December 31, 2025 and 2024 did not contain any adverse opinion or disclaimer of opinion, nor were they qualified or modified as to uncertainty, audit scope, or accounting principles. During the fiscal years ended December 31, 2025 and 2024 and the subsequent interim period through May 4, 2026, there were no disagreements (as defined in Item 304(a)(1)(iv) of Regulation S-K and the related instructions) with Grant Thornton on any matter of accounting principles or practices, financial statement disclosure, or auditing scope or procedures, which disagreements, if not resolved to Grant Thornton’s satisfaction, would have caused Grant Thornton to make reference thereto in their reports.

There were no “reportable events” (as that term is defined in Item 304(a)(1)(v) of Regulation S-K) during either of the years ended December 31, 2024 and 2025, and the subsequent interim period through May 4, 2026, except for the material weakness in the Company’s operation of controls over its review of technical accounting analysis, as first disclosed in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2024, which material weakness was remediated as of December 31, 2025.

The Company provided Grant Thornton with a copy of this Current Report on Form 8-K prior to its filing with the United States Securities and Exchange Commission (the “SEC”) and requested that Grant Thornton furnish a letter addressed to the SEC stating whether or not it agrees with the statements made herein, as specified by Item 304(a)(3) of Regulation S-K. A copy of Grant Thornton’s letter, dated May 8, 2026, is filed as Exhibit 16.1 to this Current Report on Form 8-K.

(b) Appointment of New Independent Registered Public Accounting Firm

As a result of the process noted above and following the review and evaluation of proposals from all participating firms, on May 4, 2026, the Committee approved the appointment of PricewaterhouseCoopers LLP (“PwC”) as the Company’s independent registered public accounting firm for the fiscal year ending December 31, 2026.

During the fiscal years ended December 31, 2025 and 2024 and the subsequent interim period through May 4, 2026, neither the Company nor anyone on its behalf consulted with PwC regarding the application of accounting principles to a specified transaction, either completed or proposed, the type of audit opinion that would have been rendered on the Company’s consolidated financial statements, or any matter that was the subject of a “disagreement” (as that term is defined in Item 304(a)(1)(iv) of Regulation S-K and the related instructions) or any “reportable event” (as that term is defined in Item 304(a)(1)(v) of Regulation S-K) or any other matters set forth in Item 304(a)(2)(i) or (ii) of Regulation S-K.

Item 9.01. Financial Statements and Exhibits.

(d) Exhibits.

Exhibit No.		Description
16.1		Grant Thornton’s letter

104		Cover Page Interactive File (the cover page tags are embedded within the Inline XBRL document).

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 hereunto duly authorized.

	APPLIED OPTOELECTRONICS, INC.


	By:	/s/ Stefan J. Murry
		Stefan J. Murry
		Chief Financial Officer

Date: May 8, 2026

Source: View Original Filing on SEC EDGAR

Filing Exhibits & Attachments

4 documents

Applied Optoelectronics switches auditor to PwC

Rhea-AI Filing Summary

Positive

Negative