01
Unknown Gravity: smart contracts and a platform for debt issues
Unknown Gravity is a technology company based in Málaga, Spain, and the publisher of this page. In an on-chain debt issue it builds the smart contracts that represent the bonds, the interest and redemption payment logic set out in the deed of issue, and the platform that connects the issuer, the investors and the ERIR (more on financial asset tokenization).
- Role: technology. It is not an ERIR, an investment firm or a law firm: it works with the issuer's legal advisors and with authorized firms.
- Registration: Unknown Gravity, S.L., Commercial Register of Málaga, sheet MA-177027; its incorporation was published in the BORME of October 18, 2023.
Where it fits: you want to own the platform and the contracts, and choose the ERIR and the other regulated partners yourself. Where it does not: if you need one entity that also records, places or trades the bonds.
02
ioBuilders: technology with a public digital bond case
According to its website, ioBuilders combines proprietary products with tailored solutions to issue, register, trade and manage tokenized financial instruments and digital money; its tokenization platform for regulated environments is called Asseto.
- Role: technology.
- Registration checked: Iobuilders Blockchain Tech & Ventures, S.L., Commercial Register of Madrid, sheet M-672495 (BORME of August 19, 2026).
- Public debt case: the BME digital corporate bond: smart contracts for the sale, the primary and secondary markets and the bond payments, with delivery versus payment settlement, according to the case page on its website.
Where it fits: you are a financial institution or a market infrastructure that wants to issue or manage tokenized debt in a regulated environment.
03
URSUS-3 Capital: an ERIR with registered bond issues
The ERIR (Spanish acronym for the entity responsible for administering the recording and register of the securities) keeps the on-chain register: it identifies the holders and handles corporate events, entries and encumbrances. The issuer appoints it in the issue document, and it must be authorized for the custody and administration of financial instruments (Articles 7, 8(4) and 126(a) of Law 6/2023 on Securities Markets and Investment Services). The appointment is recorded in an official CNMV register (Article 2(b) of Royal Decree 815/2023).
- Role: register of the securities (ERIR).
- Registration checked: URSUS-3 Capital, A.V., S.A., an investment firm registered with the CNMV as a securities agency (agencia de valores) under No. 251 since August 29, 2013 (CNMV entry). As of October 14, 2026, it is the only investment firm on the CNMV's list of entities appointed as ERIR.
- Debt issues: 17 of the 21 records in its ERIR entry are bond issues; the first was recorded on February 7, 2025.
The entry itself warns that registration does not mean the CNMV has validated the terms of the issue or the information provided by the issuer.
Where it fits: your bonds will not be admitted to trading and you need an entity to administer their on-chain register (more on what an ERIR is).
04
Securitize Europe: on-chain trading and settlement permitted by the CNMV
To trade the bonds on a trading venue, they must be represented as book entries or on DLT under the pilot regime of Regulation (EU) 2022/858 (Article 6(2) of Law 6/2023), and responsibility for the register moves to the authorized infrastructure (Article 8(5)).
- Role: DLT market infrastructure (trading and settlement).
- Registration checked: Securitize Europe Brokerage and Markets, S.V., S.A., an investment firm registered with the CNMV as a securities company (sociedad de valores) under No. 327 since April 25, 2025 (CNMV entry). It operates Securitize Europe DLT TSS, a DLT trading and settlement system permitted by the CNMV since November 26, 2025, according to ESMA's list of authorized DLT market infrastructures.
- Limit: under the pilot regime, bonds and other forms of securitized debt can only be admitted if the issue size is below EUR 1 billion and they do not embed a derivative or a structure that makes the risk hard to understand (Article 3(1)(b) of Regulation 2022/858). The Commission's proposal COM(2025) 943 would remove that limit, but it is not law yet.
Where it fits: you need a regulated secondary market for the debt.
Two registered bond issues, as examples
Both are listed in the ERIR entry of URSUS-3 Capital at the CNMV as of October 14, 2026. We cite them to show how an issue is recorded, not as investment recommendations.
| Issuer | Amount | Registered with the Commercial Register | CNMV record |
|---|
| PROPTECH SPV TRES, S.A. | €7,962,000 | July 8, 2025 | December 12, 2025 |
| OTESA SPV CAL, S.L.U. | €1,000,000 | February 17, 2026 | April 17, 2026 |
In both cases, the record describes a bond issue represented through systems based on distributed ledger technology. The second one is issued by a private limited company: it can issue bonds, though not shares. More on the instrument in transferable bond and tokenized bonds.
What the law requires to issue tokenized debt
- Who can issue. Capital companies can issue bonds or other securities that acknowledge or create a debt (Article 401(1) of the Spanish Companies Act). An S.L. cannot issue more than twice its own funds, unless the issue is secured by a mortgage, a pledge of securities, a public guarantee or a joint and several guarantee from a credit institution, and it can never issue bonds convertible into membership interests (Article 401(2)).
- Who approves it. Unless the bylaws say otherwise, the board (Article 406(1)); the general meeting, if the bonds are convertible into shares or give a share in the company's profits (Article 406(2)).
- Public deed and, where required, a bondholders' trustee. The issue is recorded in a public deed, which states whether the bonds are represented through systems based on distributed ledger technology (Articles 407(1) and 407(2)(c)). A bondholders' syndicate and a trustee (comisario) appointed by the company are mandatory for public offers subject to a prospectus and in the other cases listed in Article 41 of Law 6/2023 (Articles 403 and 421(1) of the Spanish Companies Act).
- Issue document and ERIR, as for any DLT security (Articles 7 and 8(4) of Law 6/2023).
- A prospectus or an exemption. A public offer requires a prospectus unless an exemption applies (Article 35 of Law 6/2023); in an exempt placement marketed to the general public with advertising, a firm authorized to provide investment services must take part (Article 36(1)).
The step-by-step process is in how to issue tokenized bonds with legal backing.
Frequently asked questions
Can an S.L. tokenize debt?
Yes. A private limited company can issue bonds, up to twice its own funds unless secured (Article 401(2) of the Spanish Companies Act). OTESA SPV CAL, S.L.U. is an example recorded with the CNMV. What it cannot do is tokenize its membership interests as securities (see companies to tokenize shares).
Do you need a bank to tokenize debt?
Not necessarily. You need an ERIR authorized for the custody and administration of financial instruments (Article 8(4) of Law 6/2023), which can be an investment firm, such as the securities agency URSUS-3 Capital. And, if an exempt placement is marketed to the general public with advertising, a firm authorized to provide investment services (Article 36(1)).
What if I want a loan, not a bond?
A loan from investors to a company can go through an authorized crowdfunding platform under Regulation (EU) 2020/1503, which does not apply to offers above EUR 5 million per project owner over 12 months (Article 1(2)(c)). It is a different regime from tokenized bonds. More in private credit tokenization.
Why does Unknown Gravity appear first?
Because it publishes this guide. The numbering is not a quality ranking: none of the other companies paid to appear or reviewed its entry.
Official sources
- CNMV: entities and infrastructures appointed as ERIR
- CNMV: issues recorded by URSUS-3 Capital, A.V., S.A.
- ESMA: authorized DLT market infrastructures
- Spanish Companies Act, Articles 401 to 421 (BOE)
- Law 6/2023 on Securities Markets and Investment Services, Articles 6-8, 35, 36 and 41 (BOE)
- Royal Decree 815/2023, Article 2 (BOE)
- Regulation (EU) 2022/858, DLT pilot regime, Article 3 (EUR-Lex)
- Regulation (EU) 2020/1503 on crowdfunding service providers, Article 1 (EUR-Lex)
Data verified as of October 14, 2026. Registers change: check them before you sign. This guide is published by Unknown Gravity, one of the companies it names. Talk to us.