A depository of  an  undertaking  for  collective  investment  in  transferable securities (UCITS) must either have its registered office in the same EU country as that of the undertaking or be established in the EU country if its registered office is in another EU country (Directive 2009/65/EC). A fund manager of a UCITS, alternative fund or pension fund may operate only as a public limited company or European company (Directive 2011/61/EU).
"§ 286.  Persons entitled to perform fund depositary functions:
 (1) Credit institutions or investment firms may be depositaries. A depositary of a UCITS may also be the central bank of an EEA Member State.

 (2) The depositary of a fund established or founded in Estonia must be entered in the Estonian commercial register as a public limited company or a branch of a foreign company.

 (3) The depositary of a fund offered in Estonia and established or founded in an EEA Member State may be a foreign credit institution or investment firm if it has the right pursuant to the law of its home country to provide services equivalent to the securities of holding services specified in clause 44 1) of the Securities Market Act and the level of supervision exercised over it is equivalent to supervision exercised over a credit institution or investment firm of the European Union.

 (4) The depositary of a non-public alternative fund, which units or shares are not redeemed within five years after founding or establishment of the fund and pursuant to the investment policy of which the assets of the fund are in general not invested in securities traded on regulated securities markets, may be other legal entities, which perform depositary functions as part of their professional or business activities and in respect of which such entities are subject to mandatory professional registration, in addition to credit institutions and investment firms.

[...]

 (6) The persons specified in subsection (4) of this section must notify the Financial Supervision Authority before commencement of provision of the services of a depositary. The specified notification shall be deemed by the Financial Supervision Authority to grant the right to act as a depositary. Upon exercise of supervision over the persons specified in subsection (4) of this section, the Financial Supervision Authority shall have the right to implement all the measures provided for in this Act.

§ 333.  Share capital and initial capital and legal form of fund managers:
 (1) A fund manager of a UCITS, alternative fund or pension fund may operate only as a public limited company or European company.
[...]"
(Investment Funds Act (RT I, 31.12.2016, 3; last amended 12.05.2021), §§286 and 333 [unofficial translation])
Investment Funds Act (RT I, 31.12.2016, 3; last amended 12.05.2021), §§286 and 333
Directive 2009/65/EC of the European Parliament and of the Council of 13 July 2009 on the coordination of laws, regulations and administrative provisions relating to undertakings for collective investment in transferable securities (UCITS), Article 23
Directive 2011/61/EU of the European Parliament and of the Council of 8 June 2011 on Alternative Investment Fund Managers and amending Directives 2003/41/EC and 2009/65/EC and Regulations (EC) No 1060/2009 and (EU) No 1095/2010
[<a href="https://www.riigiteataja.ee/en/eli/ee/508062021001/consolide/current">Investment Funds Act</a>],[<a href="https://eur-lex.europa.eu/legal-content/EN/ALL/?uri=CELEX%3A32009L0065">Directive 2009/65/EC</a>],[<a href="https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX%3A02011L0061-20190113">Directive 2011/61/EU</a>]