Turkish Book-Entry Securities and the Central Registry (MKK): Omnibus and Foreign Depository Accounts, Title, Collateral and Attachment under Communiqué II-13.1

Turkish listed shares exist only as electronic records. They are issued in book-entry form and the rights attached to them are tracked by the Central Registry Agency (Merkezi Kayıt Kuruluşu, MKK), with the records kept by MKK’s members, the brokers, banks and other institutions connected to its system (Capital Markets Law Art. 13). Shares are held in accounts opened in the holder’s name, whether registered or bearer, unless SPK allows collective accounts (Art. 13(2)); since 2019 foreign central securities depositories can hold securities of non-residents in collective accounts at MKK, but must disclose who the beneficial holders are when asked (Communiqué II-13.1 Art. 12/A). For rights to be enforceable against third parties, the date of notification to MKK is decisive (Capital Markets Law Art. 13(5)). The company’s share ledger follows MKK’s records without any application by the holder (Art. 13(6)). Attachments and injunctions on book-entry securities can be carried out only by MKK members (Art. 13(7)). MKK and its members are liable, according to their fault, for losses caused by incorrect records (Art. 81(5)), and MKK keeps every change in an unalterable form for ten years (II-13.1 Art. 36). This guide explains how these rules determine a foreign institution’s title, its evidence and its protection when an intermediary fails. It reflects the legislation in force as at 25 October 2026.

Why registry rules matter in the 2026 cases

When brokers are suspended, funds are liquidated and accounts are examined for manipulation, the first question for an investor is simple: what do I own, where is it recorded, and can anyone else touch it? In Turkey, the answer lies in the book-entry system run by MKK. A foreign institution’s Turkish shares are entries in accounts kept in MKK’s system by a Turkish broker, bank or, in some structures, a foreign central securities depository. Those entries decide who can vote and receive dividends, who can transfer or pledge the shares, which creditors can attach them, and what evidence of ownership exists.

The registry rules also matter as evidence. MKK keeps an unalterable record of every change for ten years; transfers between accounts must state their reason; and accounts that conceal their true nature are prohibited. In examinations of coordinated trading, these records show who held what, when and through which intermediary. This guide explains the legal framework. The duties of brokers and custodians towards their clients are covered in the guide to investment services rules.

This guide does not suggest that any intermediary or other person connected with the 2026 cases has kept incorrect records or breached any rule.

The legal framework

Book-entry issue without certificates is the rule; SPK decides which instruments and rights are tracked in book-entry form (Capital Markets Law Art. 13(1)). Certificates of instruments that are dematerialised must be delivered and become void on delivery (Art. 13(4)). MKK is a private law joint stock company established to dematerialise instruments, track them and the rights attached to them electronically by member and by right holder, and act as central depository (Art. 81(1)); SPK supervises it (Art. 81(6)).

MKK, its members and the account structure

Records of book-entry instruments and the rights attached to them are kept by MKK’s members in the electronic environment created by MKK, and accounts are opened and changed by members in accordance with the right holders’ instructions (Communiqué II-13.1 Art. 5(1)). MKK’s members are the Central Bank, issuers, investment firms, central clearing institutions and other institutions designated by SPK (Art. 4(1)(l)). Records at MKK may not be made subject to any restriction or condition other than those in the Communiqué, unless SPK decides otherwise (Art. 5(5)). Where a member corrects erroneous or incomplete records, it must notify MKK and the right holder of the correction (Art. 5(6)).

MKK’s wider role, supervision and issuers’ duties

Beyond dematerialisation and record-keeping, MKK has statutory tasks that matter to investors: it operates an electronic platform for communication between companies and their shareholders and investors in support of corporate governance, it maintains a single data bank for capital markets data whose use is governed by principles set by SPK, and it carries out other tasks assigned by SPK (Capital Markets Law Art. 81(3)). Within SPK’s rules, MKK may request information and documents from its members and inspect them on matters within its remit, and members may not refuse on the basis of confidentiality provisions in their special legislation (Art. 81(4)). SPK supervises MKK and may require MKK and its members to send any information or document, on request or regularly (Art. 81(6)).

Issuers have their own duties to MKK, and late or wrong notifications can affect investors’ entitlements. The table below lists the main ones.

Instruments that SPK decides to dematerialise must be delivered under the procedures it sets; delivered certificates become void automatically, and MKK sets the delivery and destruction procedures with SPK’s approval (Communiqué II-13.1 Art. 15). For mergers, demergers and other transactions in which a company is the universal successor, the member updates MKK’s records on the basis of documents showing the right holder’s entitlement (Art. 25(1)). How significant transactions such as mergers affect shareholders is explained in the guide to mergers, asset sales and the exit right.

Named accounts, omnibus accounts and foreign depositories

The default rule is that book-entry instruments are tracked in accounts opened in the holder’s name, whether the instruments are registered or bearer; SPK may decide that accounts be kept collectively without opening them in the right holder’s name, depending on the type of instrument and the nature of the issuer or MKK member (Capital Markets Law Art. 13(2); Communiqué II-13.1 Art. 11(1)). No account may be opened, and no record kept, in a way that conceals its true nature (II-13.1 Art. 6(7)).

Two exceptions are relevant to foreign institutions. First, foreign central securities depositories may open accounts at MKK, as members or, with SPK’s permission, linked to Takasbank’s account at MKK, which need not be tracked by right holder; SPK assesses such applications country by country (Art. 6(4)). Second, since 2019, a foreign central securities depository account may be opened in which only securities belonging to right holders resident abroad are tracked, collectively and without accounts in the holders’ names (Art. 12/A(1)). The rules for these accounts are specific:

1. 1. Disclosure on request. The foreign depository must, on request, provide ownership information on these accounts to SPK, MKK and persons or bodies authorised by law (Art. 12/A(1)).
2. 2. A local bank. It must sign a service agreement with a Turkish bank holding general custody authority; the depository and the bank are jointly and severally liable to MKK for transactions (Art. 12/A(2)).
3. 3. Full representative. The foreign depository is deemed the fully authorised representative to dispose of the securities and exercise all rights, including financial and administrative rights, in the name and for the account of the right holders, and is responsible for ensuring that its actions follow the holders’ instructions and the applicable foreign law (Art. 12/A(3)).
4. 4. No use without consent. The securities may not be used for the depository’s or third parties’ benefit outside the purpose of deposit without the right holders’ express written consent (Art. 12/A(3)), and the accounts are covered by the segregation rules of Capital Markets Law Art. 46(5)–(6) (Art. 12/A(5)).
5. 5. Court orders. Attachments, injunctions, restructuring, bankruptcy, seizure or freezing orders concerning the depository’s clients are notified by the issuing authority to the foreign depository, to be implemented under Capital Markets Law Art. 13(7) (Art. 12/A(4)).

Turkish investment firms with general custody authority may also offer custody under the same model, provided their service agreement with the client includes an obligation to disclose ownership information on request to SPK, MKK and authorised persons (Art. 12/A(7)). Separately, investment firms providing custody to clients resident abroad must keep their records, other than cash, for each right holder (Communiqué III-37.1 Art. 63(3)), and brokers opening accounts for foreign banks and brokers must obtain an undertaking that the identity of the clients for whose account they trade will be provided (Communiqué III-39.1 Art. 29(5)).

Opening accounts and the registry number

Investor accounts are opened at the request of investors by member investment firms and central clearing institutions, after the information required by MKK has been notified (Communiqué II-13.1 Art. 11(2)). When all of the investor’s information is complete, a registry number is created; in cases SPK allows, an account may be opened and the identity information completed within a period not exceeding five business days, failing which the account may be made dormant, meaning that transfers in and out are blocked (Art. 11(3)). Where the same investor opens accounts at another firm, the same registry number is used, and if several numbers are found to have been created for the same investor, MKK assigns a single one after notifying the investor (Art. 11(3)–(4)). Joint accounts record each owner’s share (Art. 11(5)).

Since the 2025 amendment, the documents needed to open accounts at investment firms for right holders resident abroad may be obtained from a central document management system offered by MKK (Art. 6(6)). Before accepting orders, an investment firm must open a custody sub-account for each client at MKK and match the client number with the registry number, and it may not accept orders from accounts without a matched registry number (Communiqué III-39.1 Art. 27(2)–(4)).

Settlement, transfers and off-exchange trades

Exchange trades are settled by the central clearing institution through the settlement pool account and the investment firms’ pool accounts at MKK, under the exchange’s settlement rules (Communiqué II-13.1 Art. 17(1)). After an exchange trade, the investment firm moves the sold instruments to a sub-account of the investor’s account opened for this purpose; on settlement day it moves them to its pool account, and their transfer to the settlement pool account closes its settlement obligations; settlement receipts are moved by the clearing institution to the firms’ pool accounts and then distributed by the firms to investor accounts (Art. 17(2)–(3)).

Changes resulting from off-exchange trades are recorded by the member to which the account is linked (Art. 17(4)). Transfers between accounts follow the same principles, and the reason for the transfer must be stated as MKK determines; members’ pool accounts may not be used for transfers between right holders’ accounts (Art. 17(5)–(6)). Recorded reasons for transfers are a valuable source of evidence when coordinated accounts are examined, because transfers of cash or securities between accounts are one of the indicators of persons acting together (Communiqué VI-104.1 Art. 3(1)(a)).

Title, third parties and the share ledger

For rights over book-entry instruments to be enforceable against third parties, the date of notification to MKK is decisive (Capital Markets Law Art. 13(5); Communiqué II-13.1 Art. 27). Book-entry rights are not embodied in certificates (II-13.1 Art. 5(3)).

For the company’s share ledger, MKK’s records are used without any application by the persons concerned (Capital Markets Law Art. 13(6); II-13.1 Art. 35(1)). The Commercial Code generally recognises as a shareholder, in relations with the company, only the person entered in the share ledger, but reserves the Capital Markets Law and related rules for registered shares tracked by MKK (Commercial Code Art. 499(4)–(5)). The practical effect is that, for listed shares, the investor does not need to apply to the company for registration; MKK’s records are the basis.

MKK keeps every change in rights relating to book-entry instruments, in its pre-change form, in an unalterable electronic form for ten years; SPK may set a longer period for investment fund records (II-13.1 Art. 36(1)). For an investor who needs to prove its holdings on a past date, or to show how and when shares moved, these records are the most reliable evidence available. How to obtain them in proceedings is discussed in the guide to obtaining and preserving evidence.

Dividends, general meetings and corporate actions

Issuers must notify MKK of decisions on financial rights by the business day after the decision and of any changes at the latest one day before the process starts (Communiqué II-13.1 Art. 18(1)). Interest and dividends on book-entry instruments are transferred to MKK’s correspondent bank on the first day of entitlement, then to the members’ accounts according to MKK’s records and immediately by the members to the right holders (Art. 18(3)). The issuer is responsible for late, wrong or incomplete notifications (Art. 18(4)). In capital increases, pre-emption rights are recorded in the accounts where the shares are held and deleted when exercised or at the end of the period (Art. 16(2)); bonus shares are credited according to the announced ratio (Art. 16(3)).

For general meetings, issuers notify MKK of the meeting date, and the list of persons entitled to attend is prepared by MKK one day before the meeting, showing shareholders, usufructuaries and their proxies, with the nominal value of their shares (Art. 20(1)–(2)); the board prepares the attendance list from this shareholder schedule (Commercial Code Art. 417(1)). The information obtained from MKK may not be given to third parties or used for other purposes (II-13.1 Art. 20(5)). For holdings through a foreign depository account, the foreign depository is the party through which administrative rights are exercised (Art. 12/A(3)). Exercising shareholder rights through custodians is explained in the guide to shareholder rights.

Collateral, pledges and investor blocking

Collateral agreements over book-entry instruments must be in writing; title may either pass to the collateral taker or remain with the provider, and if the agreement is silent, title is deemed not to pass (Capital Markets Law Art. 47(1)). On default, the collateral taker may sell the instruments, at not less than their market value if listed, or set off their value, without notice, a grace period, court or administrative permission or auction (Art. 47(4)); appropriation of collateral whose title remained with the provider is possible only if expressly agreed (Art. 47(4)(b)). Any surplus is returned to the provider (Art. 47(4)(c)). Restructuring or liquidation orders against either party do not affect the collateral, and are effective against the restructuring or liquidation authority (Art. 47(5)).

In MKK’s records, collateral, pledges and usufructs are recorded by the relevant member on receipt of the documents establishing them (Communiqué II-13.1 Art. 22(1)). Collateral and pledged instruments are tracked in sub-accounts linked to the provider’s account or in the taker’s account, with the identity of the provider recorded (Art. 22(2), (6)–(7)).

One protective tool deserves attention: holders of investor accounts and shareholder accounts may place a block on their own accounts to limit the disposal powers of the member through which the account is held, under rules set by MKK (Art. 23(1)). SPK may also make registration with MKK’s investor warning system mandatory, and transactions specified by MKK and approved by SPK may be prevented for accounts not registered (Art. 24).

Attachments, injunctions and trading bans

Injunctions, attachments and all similar administrative and judicial requests concerning book-entry instruments are carried out exclusively by MKK’s members, by creating a separate sub-account in the relevant investor or shareholder account; the provisions on collection of claims notified electronically under the relevant laws are reserved (Capital Markets Law Art. 13(7); Communiqué II-13.1 Art. 26(1)). Members must first make the necessary changes in MKK’s records using MKK’s electronic methods (Art. 26(2)). Trading bans notified by SPK are entered immediately by MKK in the relevant accounts, and members must report to SPK immediately any collateral, pledge, attachment or similar transactions on the accounts of persons subject to a trading ban (Art. 26(3)).

These rules matter for creditors as well as for holders. A foreign institution seeking to attach a defendant’s Turkish shares needs a Turkish order executed through the defendant’s MKK member, and the order must be notified to the member that holds the account; where the defendant holds through a foreign depository account, the order is notified to the foreign depository (Art. 12/A(4)). Attached shares may later be sold through official auctions on the exchange, as explained in the guide to Borsa Istanbul trading rules. Precautionary attachment and criminal seizure are explained in the guide to freezing assets.

Confidentiality and access to records

MKK’s records are confidential; giving information to persons or bodies authorised by law, or by legislation expressly authorised by law, is not a breach (Communiqué II-13.1 Art. 32(1)). Exchanges, for their surveillance under Capital Markets Law Art. 70(2), and central clearing institutions, for central counterparty operations, may obtain information by stating the purpose and giving reasons, under a protocol with MKK, and must keep it confidential (Art. 32(2)).

For a foreign institution, Article 33(2) is useful: with the right contractual links, its global custodian can receive ownership information from MKK directly, which allows reconciliation of the institution’s own records with the central registry rather than relying only on the Turkish sub-custodian. Issuers receiving ownership information must keep it confidential and may not share it unlawfully beyond persons with administrative responsibility (Art. 35(2)).

Liability for incorrect records

MKK and its members are liable, according to their fault, for losses suffered by right holders because records were kept incorrectly (Capital Markets Law Art. 81(5)). This is a specific statutory basis for claims where shares are missing, wrongly transferred or wrongly attached because of a recording error. It sits alongside the custodian’s contractual liability under the framework agreement and the mandate rules (Code of Obligations Arts. 112 and 506), the custodian’s obligation to keep complete, accurate and current records distinguishing each client’s assets (Communiqué III-37.1 Art. 63), and its obligation to reconcile with MKK daily (Art. 65). The issuer is liable for late, wrong or incomplete notifications of financial rights (II-13.1 Art. 18(4)), and the foreign depository and its Turkish service bank are jointly and severally liable to MKK for transactions on foreign depository accounts (Art. 12/A(2)).

When an intermediary fails

Investors’ cash and capital market instruments held at investment firms are kept separately from the firm’s assets and may not be attached for the firm’s debts, pledged without the investor’s prior written consent, included in its bankruptcy estate or made subject to interim injunctions (Capital Markets Law Art. 46(5)–(6)). Because holdings are recorded at MKK in sub-accounts linked to each investor’s registry number, a suspended broker’s clients’ shares can be identified at the central registry level. When a broker gives up its authorisation, assets of clients who could not be reconciled are blocked in their names at Takasbank and returned on application (Communiqué III-39.1 Arts. 59–61), and attached shares in the sub-accounts of a suspended broker can be sold through official auctions at the request of the authority concerned (Equity Market Directive Art. 32(6)). The procedures are explained in the guides to investment services rules and insolvency and client assets.

Points for foreign institutional investors

1. 1. Map the account chain. Identify whether your Turkish holdings sit in a named investor account, in a Turkish custodian’s collective account under Art. 12/A(7), or in a foreign depository account under Art. 12/A, and which entity is the MKK member.
2. 2. Know your registry number. A single registry number links your accounts across Turkish intermediaries (Communiqué II-13.1 Art. 11(3)).
3. 3. Reconcile against MKK. Use Art. 33(2) arrangements so that your global custodian can receive ownership information directly from MKK.
4. 4. Consider an investor block. Where an intermediary’s position is uncertain, a block under Art. 23 limits the member’s power to dispose of your holdings.
5. 5. Check collateral terms. If Turkish securities are given as collateral, confirm whether title passes and what appropriation rights the taker has (Capital Markets Law Art. 47).
6. 6. Preserve evidence early. MKK keeps changes for ten years (Art. 36), but claims have much shorter deadlines; obtain records while disputes are fresh.

Time limits and record periods

Frequently asked questions

Are Turkish listed shares held in certificates?

No. They are issued and tracked in book-entry form at MKK, and certificates of dematerialised instruments become void on delivery (Capital Markets Law Art. 13(1) and (4)).

Can a foreign institution hold Turkish shares through an omnibus account?

Yes, through a foreign central securities depository account or a Turkish custodian using the same model, but beneficial ownership must be disclosed on request to SPK, MKK and authorised authorities (Communiqué II-13.1 Art. 12/A).

Who exercises voting and dividend rights in a foreign depository account?

The foreign depository, as the fully authorised representative of the right holders, acting on their instructions (Art. 12/A(3)).

What determines when rights over book-entry shares bind third parties?

The date of notification to MKK (Capital Markets Law Art. 13(5); II-13.1 Art. 27).

Does a buyer of listed shares need to apply to be entered in the share ledger?

No. MKK’s records are used for the share ledger without any application (Capital Markets Law Art. 13(6); II-13.1 Art. 35(1)).

How long does MKK keep its records?

Ten years, in an unalterable form showing each change and the previous state (II-13.1 Art. 36(1)).

Who can attach book-entry shares in Turkey?

Attachments and injunctions are executed exclusively by MKK members through sub-accounts (Capital Markets Law Art. 13(7); II-13.1 Art. 26).

Can an investor protect its account against an intermediary?

Yes. Account holders may place a block on their own MKK accounts to limit the member’s disposal powers (II-13.1 Art. 23).

Is MKK liable for recording errors?

MKK and its members are liable, according to their fault, for losses caused by incorrect records (Capital Markets Law Art. 81(5)).

Can a foreign custodian obtain information directly from MKK?

Yes, where the client contract and a contract with the Turkish custodian provide for it and the Turkish custodian applies to MKK (II-13.1 Art. 33(2)).

Related guides

• Turkey’s 2026 Fund and Market Manipulation Crisis: Legal Guide for Foreign Institutional Investors — the entry point to this series
• Turkish Currency Law and Repatriation of Investment Proceeds
• Investment Services Rules in Turkey: Communiqués III-37.1 and III-39.1
• Claims against Brokers, Custodians and Portfolio Managers in Turkey
• Insolvency of Turkish Issuers and Brokers
• Freezing Assets in Turkey
• Shareholder Rights in Turkish Listed Companies
• Borsa Istanbul Trading Rules: The Equity Market Directive
• Obtaining and Preserving Evidence in Turkey for Securities Claims
• Market-Disrupting Acts in Turkey: Article 104 and Communiqué VI-104.1