How Borsa İstanbul’s collaboration with LSEG supports transparent ESG assessments, expands sustainability coverage and strengthens sustainability-related benchmarking in Türkiye’s capital markets.
Advancing Sustainability in Türkiye’s Capital Markets
Borsa İstanbul plays a central role in the development of Türkiye’s capital markets, providing market infrastructure and investment opportunities across a range of asset classes. Recognizing the importance of environmental, social and governance (ESG) considerations, Borsa İstanbul continues to develop initiatives that promote transparency, encourage responsible business practices and support informed investment decisions.
The launch of the BIST Sustainability Index in 2014 marked an important milestone in this journey. The index was designed to encourage listed companies to improve their sustainability practices while providing investors with a benchmark based on defined ESG criteria.
In 2021, Borsa İstanbul began collaborating with LSEG, incorporating its ESG data and assessment methodology into the BIST Sustainability Index framework. This marked a new phase in the index’s development, introducing an internationally established assessment approach to support transparent and consistent sustainability evaluations.
The growth of sustainable capital markets depends critically on accurate ESG data and open evaluation procedures. Through our partnership with LSEG, we have been able to greatly increase the coverage of globally recognized ESG evaluations among Türkiye's listed firms while also strengthening their utilization. We continue to be committed to giving investors relevant benchmarks, promoting more corporate transparency, and assisting the long-term growth of sustainable financing in Türkiye as sustainability standards and evaluation techniques change.
Güzhan Gülay
A Partnership Built on Trust and Transparency
Reliable and comparable ESG information plays an important role in helping investors assess sustainability-related risks and opportunities.
Through its collaboration with LSEG, Borsa İstanbul uses ESG assessments covering environmental, social and governance factors to determine eligibility for its sustainability indices that use LSEG ESG assessments. The methodology provides a structured framework for evaluating companies against defined criteria.
LSEG’s ESG data contribution tools also allow companies to review and contribute relevant sustainability information, helping support the accuracy and completeness of their assessments. This engagement encourages greater transparency in ESG reporting and enables companies to better understand the factors considered in their evaluations.
By combining LSEG’s ESG data expertise with Borsa İstanbul’s index framework, the collaboration supports a transparent and rules-based approach to sustainability-related benchmarking.
Expanding Coverage, Evolving Methodologies
Since the collaboration began in 2021, the number of companies assessed by LSEG has increased from 85 to 157 representing growth of approximately 85%.
Over the same period, the number of companies represented in the BIST Sustainability Index has increased from 59 to 100.
This expansion has broadened the reach of ESG assessments and sustainability-related benchmarking across Türkiye’s listed companies.
Eligibility for the BIST Sustainability Index is determined by defined ESG performance thresholds. Companies must meet minimum overall ESG scores and minimum scores across the environmental, social and governance pillars, with the applicable selection rules governing index inclusion.
Alongside this growth, the collaboration continues to adapt to developments in LSEG’s ESG assessment methodology. In 2026, LSEG introduced an updated ESG scoring methodology based on a 0–5 scale, alongside its established 0–100 methodology.
The methodological transition is ongoing. Borsa İstanbul currently uses both methodologies within its sustainability index selection framework, applying the relevant eligibility criteria under each approach. No end date for this parallel use has been announced.
Expanding Sustainability-Related Investment Opportunities
Borsa İstanbul has continued to broaden its sustainability-themed index offering, providing benchmarks designed to address different investment needs.
Building on the BIST Sustainability Index, the BIST Sustainability 25 Index was launched in November 2022. It comprises 25 shares selected from eligible companies meeting higher ESG performance thresholds, with trading volume and market capitalisation also considered under its selection rules.
The BIST Participation Sustainability Index expands the range of available benchmarks by combining sustainability-related eligibility requirements with participation finance criteria.
Beyond equities, Borsa İstanbul has introduced sustainability-themed debt securities indices designed to measure the daily returns of eligible green and sustainable debt instruments under the relevant regulatory framework. These fixed-income indices form part of Borsa İstanbul’s broader sustainability offering and should not be understood as indices selected using LSEG ESG scores. The selection pool of Eurobonds to be included in the indices includes Eurobonds issued by Turkish companies in USD abroad, which have been qualified as "Green Debt Security" or "Sustainable Debt Security" with the Capital Markets Board of Türkiye (CMB) approval obtained in accordance with the terms specified in the Guidelines.
Together, these developments reflect Borsa İstanbul’s efforts to expand sustainability-related benchmarking across different segments of Türkiye’s capital markets.
Building on Progress
As sustainability considerations become increasingly integrated into investment analysis and corporate reporting, reliable ESG data and transparent assessment frameworks remain important.
Borsa İstanbul’s collaboration with LSEG has evolved alongside the expansion of ESG assessment coverage and developments in sustainability assessment methodologies. The continued use of LSEG’s ESG data supports a structured approach to sustainability-related index selection.
Looking ahead, Borsa İstanbul aims to expand its sustainability-themed index offering by exploring new benchmarks that respond to evolving investor needs. Its ongoing collaboration with LSEG will continue to support ESG transparency and sustainability-related benchmarking in Türkiye.
Our collaboration with LSEG is not only helping us to improve transparency and access to data — we are making a real-world impact by helping to create a better environment overall for capital markets in Türkiye.
