Introduction
Borsa İstanbul regulations and capital market compliance in Turkey are essential for companies, investors, brokerage firms, portfolio management companies, foreign issuers, institutional investors and all market participants operating in Turkish capital markets. Borsa İstanbul is not only a trading venue. It is a regulated market infrastructure where shares, debt securities, derivatives, precious metals, funds and other financial instruments are traded under rules designed to ensure transparency, fairness, efficiency, stability and investor protection.
The legal framework of Borsa İstanbul is closely connected with Capital Markets Law No. 6362, the secondary regulations of the Capital Markets Board of Türkiye, known as the CMB in English and SPK in Turkish, the Turkish Commercial Code, Borsa İstanbul directives, market procedures, Public Disclosure Platform rules and clearing and settlement infrastructure. Borsa İstanbul explains that Capital Markets Law No. 6362 repealed the previous capital market and securities exchange framework, restructured the former İstanbul Stock Exchange as Borsa İstanbul, and established stock exchanges as private law legal entities authorized under the new legal regime.
For companies, compliance with Borsa İstanbul regulations is necessary before and after listing. For investors, these regulations provide market transparency, fair trading conditions and access to public information. For brokerage firms and investment institutions, compliance is a daily operational obligation involving order transmission, trading rules, market surveillance, customer protection and reporting. For foreign investors, understanding Borsa İstanbul rules is crucial before investing in listed Turkish companies or participating in public offerings.
Legal Framework of Borsa İstanbul
The legal framework of Turkish capital markets is mainly based on Capital Markets Law No. 6362 and the Turkish Commercial Code, supported by detailed secondary legislation such as CMB communiqués and Borsa İstanbul regulations. Borsa İstanbul’s official legal framework page expressly states that the current legal framework is mainly devised by these two major pieces of legislation, with detailed regulation through CMB communiqués and stock exchange regulations.
This layered structure means that capital market compliance in Turkey cannot be analyzed only by reading one statute. A listed company must comply with the Capital Markets Law, CMB disclosure rules, Borsa İstanbul listing rules, KAP procedures, corporate governance requirements and financial reporting standards. A brokerage firm must comply with CMB investment services rules, Borsa İstanbul trading procedures, order execution principles, risk management requirements and customer asset protection rules. An investor must also understand that trading on Borsa İstanbul occurs within a regulated environment, but market risk remains.
Borsa İstanbul publishes various directives and procedures that form part of the practical regulatory framework. Its official regulations page lists documents such as the Equity Market Directive, Listing Directive, Derivatives Market Directive, Directive on Surveillance Measures, Directive on Granting Authorization to Trade at Borsa İstanbul, Debt Securities Market Directive and market procedures. These documents are highly important for market participants because they determine how instruments are listed, traded, monitored and supervised.
Markets Operated by Borsa İstanbul
Borsa İstanbul operates multiple markets. The most widely known is the Equity Market, where shares of listed companies are traded. It also operates the Debt Securities Market, Derivatives Market, known as VIOP, Precious Metals and Diamond Market, and other specialized market platforms. Borsa İstanbul’s investment guide identifies these markets and provides separate information for equity, debt securities, derivatives, precious metals and private market structures.
The Equity Market is especially important because it provides investment access to major Turkish companies operating in different sectors. Borsa İstanbul states that Equity Market segments are defined based on criteria such as market capitalization, free float and liquidity, and that the main equity market segments are BIST Stars, BIST Main and BIST SubMarket.
VIOP, the Derivatives Market, is also significant for professional investors and risk management. Borsa İstanbul describes VIOP as the market where derivatives contracts are traded on underlying assets such as single stocks, indices, foreign currencies, energy, commodities, precious metals, foreign indices, metals, TLREF and government bonds. It also states that VIOP provides opportunities such as hedging, portfolio diversification, leverage, effective price formation and access to liquidity.
Borsa İstanbul Listing Rules
Listing is one of the most important compliance stages for companies. A company whose shares are to be traded on Borsa İstanbul must satisfy relevant listing requirements. These requirements are designed to ensure that companies entering the public market have sufficient operational history, financial strength, shareholder equity, public float and legal compliance.
Borsa İstanbul explains that, for company shares to be traded on BIST Stars, BIST Main or BIST SubMarket, the company must meet specific requirements. The official listing requirements page states that BIST Stars is the market for shares with a free-float market value equal to or above TRY 1 billion, BIST Main is for shares with a free-float market value between TRY 1 billion and TRY 250 million, and BIST SubMarket is for shares below TRY 250 million by free-float market value.
The same official page lists current minimum requirements for market value of shares offered to the public: TRY 1 billion for BIST Stars, TRY 250 million for BIST Main, and TRY 100 million for BIST SubMarket. It also lists minimum public offering ratios of 10% for BIST Stars, 20% for BIST Main, and 25% for BIST SubMarket, together with audited net profit requirements for the last two years and shareholders’ equity to capital ratio thresholds.
These requirements are highly relevant for IPO planning. A company considering public offering must determine which market segment it may qualify for and whether its financial statements, capital structure, free float and profitability satisfy the relevant standards. If the company does not meet the criteria, the public offering timetable, valuation, capital increase structure or market segment strategy may need to be revised.
Public Offering and Listing Process
Public offering and listing are connected but distinct processes. Public offering generally refers to the sale of shares to a broad investor base, while listing refers to admission of securities to trading on Borsa İstanbul. Borsa İstanbul defines public offering as the sale of shares through call and announcement to a large number of previously unknown investors. It also states that companies applying to be listed on BIST Stars, BIST Main and BIST SubMarket may offer existing shares, conduct a public offering through capital increase by restricting existing shareholders’ priority rights, or use both methods together.
This distinction matters legally. In a capital increase-based IPO, the company receives new funds and strengthens its equity. In a sale of existing shares, existing shareholders receive the proceeds. A combined offering may allow both company financing and shareholder liquidity. The structure must be clearly disclosed in the prospectus and offering documents.
The public offering process requires CMB approval of the prospectus where applicable, compliance with CMB rules on sales of capital market instruments, satisfaction of Borsa İstanbul listing criteria and preparation of public disclosure infrastructure. A company should also conduct legal due diligence before applying. Common legal issues include defective share transfers, privileged share structures, transfer restrictions, unresolved litigation, related-party transactions, tax risks, regulatory permits and corporate governance weaknesses.
Listing of Debt Securities
Borsa İstanbul regulations are not limited to shares. Debt securities issued through public offering may also be listed, subject to specific requirements. Borsa İstanbul states that, for debt securities issued through public offering to be listed, at least two calendar years must have passed since the issuer’s establishment, the issuer’s recent CMB-compliant audited financial statements must show total shareholders’ equity greater than capital, and the issuer must have obtained net profit in at least one of the last two annual accounting periods.
The same official page also requires that the issuer’s financial situation allow it to continue business operations in a healthy manner and that the issuer not be subject to significant legal disputes affecting its production or other activities. It further requires a legal report issued by an independent lawyer confirming that the issuer’s establishment, operations and debt securities comply with applicable laws and regulations.
This legal report requirement is important. It shows that capital market compliance is not only a financial review. Borsa İstanbul expects legal verification of the issuer’s status, operational legality and securities structure. Companies planning debt securities offerings should therefore begin legal due diligence early.
Equity Market Trading Principles
Trading rules are a central part of Borsa İstanbul compliance. Borsa İstanbul states that Equity Market trading is carried out through a fully automated electronic trading system based on price and time priority, using trading methods such as continuous trading, continuous trading with market maker and single-price trading. It also states that clearing and settlement of securities and cash in the Equity Market are realized on a T+2 basis.
The price and time priority rule is fundamental. Borsa İstanbul explains that, under price priority, lower-priced sell orders are matched before higher-priced sell orders, and higher-priced buy orders are matched before lower-priced buy orders. Under time priority, where prices are equal, earlier orders have priority.
These rules protect fairness and predictability. Investors and brokerage firms must understand that orders are not matched arbitrarily. The system prioritizes economically better prices and then earlier orders. For investment institutions, compliance requires proper order entry, accurate customer instruction recording and avoidance of conduct that may manipulate order priority.
Price Limits, Price Ticks and Circuit Breakers
Borsa İstanbul applies trading mechanisms designed to reduce extreme volatility and protect market integrity. The official Equity Market page states that daily price limits apply to stocks traded in the Equity Market and that circuit breakers are triggered when predetermined thresholds are reached to reduce risks from market-wide or stock-specific volatility.
Borsa İstanbul’s market functioning page states that, until further notice, a 10% price margin applies for equities in BIST Stars, BIST Main, exchange traded funds, real estate certificates, real estate investment funds and venture capital investment funds. It also provides detailed price tick tables for stocks, pre-emptive rights and exchange traded funds.
Borsa İstanbul also explains that circuit breaker price limits and order collection phases vary by market. The market functioning page states that the price difference from the reference price for the circuit breaker to trigger is 10% for BIST Stars, 7.5% for BIST Main, and 5% for BIST SubMarket, with order collection and matching phase durations specified for each market. However, Borsa İstanbul’s Equity Market markets page notes that, under current applications implied by announcements and CMB decisions, circuit breakers for all equities are triggered at 5% and in downward trend only, with a 10-minute order collection period for all equities until further notice.
These mechanisms are important for investors and compliance officers. Price limits and circuit breakers do not eliminate market risk, but they provide structured pauses and order collection periods during abnormal volatility. Brokerage firms must ensure that their systems reject orders outside price margins, comply with price ticks and handle circuit breaker events properly.
Short Selling and Market Stability Measures
Short selling is another sensitive area of Borsa İstanbul and CMB regulation. Borsa İstanbul’s Equity Market page states that, pursuant to the CMB decision dated 6 February 2023, the short selling ban imposed on the Borsa İstanbul Equity Market was lifted from stocks listed within the BIST 50 Index as of 2 January 2025 pursuant to the CMB decision dated 5 December 2024.
This shows that short selling regulation in Turkey may change depending on market conditions, CMB decisions and stability concerns. Market participants must therefore check current CMB and Borsa İstanbul announcements before relying on general assumptions. A short selling strategy that is permitted for certain instruments or periods may be restricted under market-wide or stock-specific measures.
Short selling compliance requires strict attention to disclosure, borrowing, settlement, order marking, margin requirements and restrictions. Brokerage firms must also monitor whether their clients are allowed to short sell the relevant instrument and whether special market measures apply.
Public Disclosure Platform and KAP Compliance
Public disclosure is one of the strongest pillars of Borsa İstanbul compliance. The Public Disclosure Platform, known as KAP, is the electronic system through which electronically signed notifications required by capital markets and Borsa İstanbul regulations are publicly disclosed. KAP is operated by Merkezi Kayıt Kuruluşu A.Ş. on a 7/24 basis and is designed to provide correct, timely, fair and complete information about Borsa İstanbul companies simultaneously and at low cost.
For listed companies, KAP compliance is mandatory. Financial statements, material event disclosures, dividend decisions, capital increases, mergers, acquisitions, related-party transactions, general assembly announcements, share buybacks and other regulated disclosures must be made through proper channels. A company that delays or misstates a KAP disclosure may face CMB sanctions, investor claims and market credibility loss.
For investors, KAP is the most reliable source of public information. Investment decisions should be based on official disclosures rather than rumors, unofficial social media posts or informal investor group messages. For foreign investors, KAP is also essential because it provides public access to listed company disclosures in a structured electronic environment.
Corporate Governance and Listed Company Compliance
Companies traded on Borsa İstanbul must comply with corporate governance principles and capital market regulations. Compliance includes board responsibilities, independent directors where applicable, investor relations, related-party transactions, shareholder rights, general assembly procedures, financial reporting, internal control and material event disclosure.
The CMB’s legal framework includes the Communiqué on Corporate Governance and other issuer-related regulations such as rules on dividends, buy-backs, mergers, demergers, takeover bids, squeeze-out and sell-out rights, and voting by proxy.
Corporate governance is not merely a formal requirement. It directly affects investor confidence and valuation. Companies with weak disclosure practices, opaque related-party transactions or controlling shareholder conflicts may face investor distrust and regulatory scrutiny. Listed companies should maintain internal governance systems capable of identifying material developments and ensuring accurate disclosure.
Market Surveillance and Manipulation Compliance
Market surveillance is a core function of Borsa İstanbul and CMB supervision. Borsa İstanbul publishes a Directive on Surveillance Measures, indicating that surveillance is part of the exchange’s formal regulatory infrastructure. Surveillance measures may become relevant where unusual price movements, suspicious order activity, market abuse, manipulation or insider trading concerns arise.
Market manipulation has been a major regulatory concern in Turkey. Reuters reported in November 2025 that Turkish authorities were considering tougher penalties and new regulations against market manipulation, particularly in relation to certain investment funds, and that potential measures discussed included higher fines and cancellation of portfolio management licenses. Reuters also reported in February 2025 that Turkish authorities launched an investigation into misleading and manipulative news that allegedly caused unusual price and volume movements in Istanbul’s stock market, with the CMB and Borsa İstanbul reviewing transactions.
For listed companies, brokerage firms and investors, this enforcement environment shows that compliance must be taken seriously. Suspicious trading, misleading announcements, social media-driven campaigns, artificial order patterns and dissemination of false news may create serious administrative, civil and criminal risks.
Algorithmic Trading and Pre-Trade Risk Management
Modern exchange compliance also includes technology-driven controls. Borsa İstanbul’s procedures page lists the Equity Market Algorithmic Trading and BISTECH PTRM/Pre-Trade Risk Management Procedure, uploaded on 28 March 2025. This shows that algorithmic trading and pre-trade risk management are part of Borsa İstanbul’s current operational framework.
Algorithmic trading can improve liquidity and execution efficiency, but it also creates risks. Erroneous algorithms, excessive order submission, rapid cancellations, system overload, manipulative patterns and insufficient risk limits may harm market integrity. Brokerage firms and members must therefore implement pre-trade risk controls, order limits, monitoring systems and emergency procedures.
For investment institutions, technology compliance is no longer optional. Digital order channels, mobile applications, API trading, algorithmic execution and high-frequency strategies require legal and operational review. Errors may lead not only to financial losses but also to regulatory sanctions.
Member Compliance and Authorization to Trade
Borsa İstanbul trading is conducted through authorized members and investment institutions. Borsa İstanbul’s directives list includes the Directive on Granting Authorization to Trade at Borsa İstanbul A.Ş., which shows that access to exchange trading is subject to formal authorization.
Members must comply with exchange rules, CMB regulations, order entry principles, risk management requirements, client protection rules, surveillance obligations and technical standards. A brokerage firm cannot treat Borsa İstanbul access as a simple commercial connection. It is a regulated market membership and trading permission structure.
Member compliance includes customer onboarding, order recording, risk controls, suspicious transaction monitoring, settlement obligations, margin requirements, market conduct rules and cooperation with regulatory authorities. Failures may lead to disciplinary measures, trading restrictions, administrative sanctions and civil liability toward clients.
Capital Market Compliance for Issuers
Issuers listed on Borsa İstanbul must maintain continuous compliance. This includes timely KAP disclosures, financial reporting, corporate governance obligations, shareholder communications, general assembly procedures, compliance with listing requirements and cooperation with Borsa İstanbul and CMB inquiries.
A listed company should have a disclosure committee or internal process to identify material information. It should also train senior managers, investor relations personnel and board members on disclosure rules. Public statements, investor presentations, press releases and social media posts must be consistent with KAP disclosures.
Issuers should also monitor whether they continue to satisfy listing conditions. Changes in free float, market value, financial position, profitability, shareholder equity, legal disputes or corporate structure may affect market segment status or trigger Borsa İstanbul review.
Capital Market Compliance for Investors
Investors trading on Borsa İstanbul should understand both market opportunities and compliance risks. Investors must not trade on inside information, participate in manipulative schemes, spread false information, coordinate artificial trading through groups or use nominee accounts to bypass trading restrictions.
Investors should also understand trading mechanics. Price limits, circuit breakers, price ticks, T+2 settlement, short selling restrictions and market segment rules may affect execution and liquidity. In volatile periods, orders may not be executed as expected, circuit breakers may pause trading, and price limits may prevent immediate exit.
Retail investors should rely on KAP disclosures and authorized investment institutions. They should be cautious about social media claims, Telegram or WhatsApp groups, guaranteed-profit promises and rumors about listed companies. Such communications may be misleading or manipulative.
Capital Market Compliance for Foreign Investors
Foreign investors can participate in Borsa İstanbul markets through appropriate account, custody and brokerage structures. However, foreign investors must comply with Turkish market conduct rules, disclosure obligations where applicable, beneficial ownership requirements, tax documentation, custody procedures and anti-money laundering rules.
Foreign investors acquiring significant stakes in listed Turkish companies may trigger disclosure obligations or takeover bid rules depending on the transaction. Foreign investors participating in private placements, block trades or strategic acquisitions must also consider insider trading risks if they receive non-public information during due diligence.
Foreign brokers and fintech platforms should be especially cautious. A foreign license does not automatically authorize investment services in Turkey. If a platform targets Turkish residents, Turkish CMB licensing rules may apply.
Common Compliance Risks on Borsa İstanbul
Common compliance risks include delayed material event disclosure, misleading KAP announcements, insufficient risk factors in prospectuses, unauthorized investment advice, defective order recording, suspicious account relationships, manipulation through social media, trading during blackout periods, failure to comply with short selling restrictions, improper public offering marketing and weak corporate governance controls.
For issuers, the most serious risks usually arise from disclosure failures and related-party transactions. For brokerage firms, risks often arise from order execution, customer classification, margin calls, custody, suspicious trading and recordkeeping. For investors, risks include trading on rumors, participating in manipulation and misunderstanding market mechanisms.
Compliance should therefore be proactive. It is not enough to react after a CMB inquiry or Borsa İstanbul warning. Companies and institutions should build internal systems before violations occur.
Practical Compliance Checklist for Listed Companies
A company listed on Borsa İstanbul should maintain a structured compliance program. The program should include KAP disclosure procedures, insider information controls, financial reporting calendars, investor relations policies, board approval procedures, related-party transaction review, corporate governance reporting, crisis disclosure protocols and periodic legal audits.
The company should also ensure that all public communications are reviewed. Investor presentations, website content, press interviews, analyst meetings and social media statements should not contradict KAP disclosures or selectively reveal material information. When in doubt, legal counsel should be consulted before publication.
Practical Compliance Checklist for Brokerage Firms
Brokerage firms should ensure that their systems comply with Borsa İstanbul trading rules. They should monitor price limits, price ticks, circuit breaker events, short selling restrictions, order recording, customer risk limits, margin requirements, suspicious transaction patterns and pre-trade risk controls.
They should also train customer representatives. Employees should not provide unauthorized investment advice, spread rumors, encourage speculative manipulation or misrepresent trading risks. All client communications and order instructions should be properly documented.
Practical Compliance Checklist for Investors
Investors should check KAP disclosures before making decisions. They should understand whether the instrument is traded on BIST Stars, BIST Main, BIST SubMarket or another market. They should also understand daily price limits, circuit breakers, T+2 settlement, liquidity risk and short selling restrictions.
Investors should avoid coordinated trading groups and guaranteed return claims. They should preserve account statements, order confirmations, screenshots and broker communications if a dispute arises. If they suspect manipulation, unauthorized transactions or misleading disclosure, they should seek legal advice promptly.
Conclusion
Borsa İstanbul regulations and capital market compliance in Turkey form a comprehensive legal and operational framework for listed companies, investors, brokerage firms, foreign institutions and other market participants. The system is based on Capital Markets Law No. 6362, CMB communiqués, Borsa İstanbul directives, market procedures, KAP disclosure rules and market surveillance mechanisms.
Borsa İstanbul’s legal framework reflects the transformation of Turkish capital markets under Capital Markets Law No. 6362, which restructured the former İstanbul Stock Exchange as Borsa İstanbul and established stock exchanges as private law legal entities operating under a regulated capital market system.
For issuers, compliance begins before listing and continues throughout public company life. Listing requirements, prospectus rules, KAP disclosures, corporate governance duties, financial reporting and market segment rules must be followed carefully. For brokerage firms, compliance involves authorization, trading rules, order recording, pre-trade risk controls, customer protection, suspicious transaction monitoring and cooperation with Borsa İstanbul and the CMB. For investors, compliance means trading through authorized institutions, relying on official disclosures, avoiding market abuse and understanding exchange trading mechanisms.
In conclusion, Borsa İstanbul compliance is not merely a technical market procedure. It is the legal foundation of trust, transparency and investor protection in Turkish capital markets. Any company planning an IPO, any investor acquiring a significant stake, any brokerage firm providing trading access, or any foreign institution targeting Turkish capital markets should obtain professional legal advice before acting.
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