Hong Kong's largest issuers are about to sit two different climate exams on the same set of data. On the Mainland side, major A-share constituents and dual-listed groups have just completed their first mandatory sustainability reporting cycle, with FY2025 reports generally due by 30 April 2026. On the Hong Kong side, Hang Seng Composite LargeCap Index (HSCLI) constituents that remained in the index throughout the prior year must now report Part D climate-related disclosures under HKEX's ESG Reporting Code (Appendix C2) on a mandatory basis for financial years commencing on or after 1 January 2026, with those ESG reports typically published in 2027.
At the same time, Hong Kong is moving towards full adoption of HKFRS S1 and HKFRS S2 sustainability disclosure standards no later than 2028, with HKEX expected to consult in 2027 on mandating them for large publicly accountable entities. Public summaries of the CFA Institute's 2026 China Green Finance and ESG Investment survey underline the challenge: disclosure mechanisms remain uneven, standards are not fully unified, and nearly every respondent reports some form of talent capability gap, even as most say they have advanced green-finance work.
Our view is that frameworks are not the bottleneck. The real risk is dual-track data without a single operating model: one inventory, two clocks. Issuers that try to satisfy HKEX Part D by rebadging a Mainland first-year sustainability report will look compliant on checklists and still fail investors on financial-effect materiality, Scope 3 narrative quality and transition-plan credibility.
Problem: The dual deadline is not the same exam twice
On paper, Mainland sustainability reporting guidelines and HKEX Appendix C2 Part D both lean on ISSB-style architecture. That resemblance is exactly what misleads boards.
Under HKEX's 2024 climate amendments:
- All listed issuers must disclose Scope 1 and Scope 2 greenhouse gas emissions on a mandatory basis for financial years commencing on or after 1 January 2025.
- Main Board issuers must report Part D Climate Requirements on a comply-or-explain basis, with GEM issuers encouraged to report voluntarily.
- For financial years commencing on or after 1 January 2026, HSCLI constituents throughout the immediately preceding year must report Part D on a mandatory basis, and once an issuer enters that regime it remains in it even if it later leaves the index.
At the same time, HKICPA has published HKFRS S1 and HKFRS S2, fully aligned to IFRS S1 and S2, with a roadmap for large publicly accountable entities to adopt the standards by 2028.
For dual-listed groups, the practical problem is organisational, not conceptual:
- Different audiencesMainland first-cycle packs often optimise for domestic topic coverage and multi-stakeholder expectations. Part D explicitly asks for climate-related risks and opportunities that could reasonably be expected to affect cash flows, access to finance or cost of capital over short, medium and long term, with investor-useful information kept clearly identifiable.
- Different "explain" culturesUnder Appendix C2, "comply or explain" rewards specific reasons, forward plans and progress disclosure. Vague explanations that simply state "data systems are being built" will age badly once LargeCap mandatory status applies and peers move ahead on scenario analysis and Scope 3.
- One team, two reporting calendarsMainland FY2025 packs are due by spring 2026; FY2026 Part D data collection for LargeCaps is already underway, with outputs due in ESG reports published in 2027. Few issuer ESG units can run two full-quality narratives in parallel without a single data spine and clear ownership of boundaries, assumptions and language.
Method: Anchor on Part D's financial materiality and build "one inventory, two clocks"
HKEX's ESG Academy guidance emphasises that Part D climate disclosures must be anchored in financial materiality: climate-related risks and opportunities that could reasonably be expected to affect cash flows, access to finance or cost of capital. Boards should document both quantitative and qualitative factors and ensure investor-relevant information is not obscured by broader ESG content.
For dual-track issuers, we recommend an operating model built on three moves.
1. Use one greenhouse-gas and climate-risk inventory
The only scalable solution is a single GHG and climate-risk inventory that supports both Mainland and Hong Kong packs. That means one set of organisational and operational boundaries; one methodology for Scope 1, 2 and prioritised Scope 3 categories; and one climate-risk register covering physical and transition risks at asset and portfolio level.
From that single inventory, you map into two disclosure "skins":
- Mainland sustainability report sections aligned to local guidance and stakeholder topics.
- HKEX Appendix C2 Parts C and D, including Part D's scenario analysis, financial-effect discussion and target disclosure.
Dual-language production for Hong Kong should use Traditional Chinese terminology consistent with listing rules (環境、社會及管治報告守則, 企業管治守則, 範圍一／二／三, 不遵守就解釋) rather than treating Simplified Mainland phrasing as a default template.
2. Deliberately separate Mainland topic coverage from Part D investor materiality
A simple internal matrix can help management avoid "copy-paste mirage":
- For Mainland packs, rows reflect topics and KPIs needed for domestic guidance and stakeholder expectations.
- For Part D, rows reflect climate-related risks, opportunities, metrics and targets that pass the investor-materiality test.
Columns indicate whether a topic is: (a) material to investors, (b) material to other stakeholders, or (c) only included for topic-coverage reasons. The ESG report can include both, but investor-material information must remain clearly sign-posted and not drowned out.
3. Treat Mainland first-year friction as a stress test for Part D
Public reporting on the CFA Institute survey and Mainland ESG first-year experience highlights three recurring issues: incomplete disclosure mechanisms, lack of unified standards and talent capability gaps, even as most respondents report active green-finance work.
Dual-listed issuers should treat every Mainland friction as a Part D dress rehearsal. Wherever Mainland reviewers, internal audit or boards highlighted data lineage weaknesses, inconsistent boundaries or unclear Scope 3 estimates, assume Hong Kong readers and sell-side analysts will press the same points using an investor-focused vocabulary: financial effects, resilience, and comparability across peers.
Implication: What HSCLI and Main Board issuers should do in FY2026
For HSCLI / LargeCap boards under mandatory Part D from FY2026
FY2026 should be treated as a control year, not just a drafting year. The ESG report you publish in 2027 will be your first under mandatory Part D. Boards should ask for:
- A reconciliation memo between the FY2025 Mainland sustainability report (if applicable) and the planned FY2026 Part D outline, with gaps and differences owned by named executives and dates.
- Evidence that climate oversight is integrated into the board's ESG governance statement rather than bolted on as a standalone chapter, in line with Appendix C2 expectations on governance and risk management.
- A transition-plan skeleton that connects initiatives to resources, timelines and any carbon-credit usage, even if quantitative financial-effect estimates are partial under HKEX's implementation reliefs.
For other Main Board issuers still on comply-or-explain
"Explain" is not a free pass through to 2028. HKEX encourages issuers to disclose work plans, progress and timetables where information is incomplete. Soft explanations that do not show movement on GHG boundaries, scenario analysis or target calibration will be harder to defend once HKFRS SDS and assurance discussions enter the mainstream. FY2026 can be used to establish the single inventory, mapping tables and control environment ahead of any future mandate.
For dual-listed groups
Stop running "Hong Kong vs Shanghai" as parallel disclosure universes. Appoint a single disclosure controller or committee with authority over:
- Boundary decisions for both packs.
- Denominators for intensity metrics.
- Scenario selection and narrative framing.
- Consistency of claims on net-zero, transition plans and carbon-credit usage.
This is as much an internal-control and risk-management topic as an ESG one. It belongs alongside Corporate Governance Code discussions on risk oversight, internal audit and ICFR, not solely within a sustainability silo.
For investors and lenders reading both packs
Expect narrative drift in 2026–2027 as issuers adapt to dual-track requirements. A simple filter is to favour companies that:
- Publish a clear mapping between Mainland metrics and Part D metrics.
- Admit uncertainties around Scope 3 and financial-effect quantification rather than smoothing them away.
- Demonstrate that "one inventory, two clocks" is an operating principle, not just a phrase.
Big-number call-outs
1 January 2026 Start of financial years from which HSCLI constituents (throughout the prior year) must report Part D Climate Requirements on a mandatory basis under Appendix C2, with ESG reports generally published in 2027.
1 January 2025 Start of financial years from which all listed issuers must disclose Scope 1 and Scope 2 emissions on a mandatory basis.
Circa 30 April 2026 Common deadline cited for major Mainland index constituents and dual-listed companies to publish first mandatory sustainability reports covering FY2025.
2028 Target date for large publicly accountable entities in Hong Kong to fully adopt HKFRS Sustainability Disclosure Standards (HKFRS S1 and S2), aligned with ISSB's IFRS S1 and S2.
~97% Share of surveyed enterprises in the CFA Institute 2026 China green-finance / ESG investment survey reporting some degree of talent capability gap, based on public media summaries.
FAQs
Conclusion
One inventory, two clocks. The competitive advantage in 2026 is not owning another framework slide. It is owning a single climate and ESG data inventory with disciplined mapping into Mainland and Hong Kong disclosure skins, so that mandatory Part D for LargeCaps does not become a second, contradictory story about the same emissions and the same board.
Edited / written by: Amanda Cheung, Founder, AMMO Group
