SBI Sumishin Net Bank → Docomo SMTB Net Bank

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This entry sits under regional-banks INDEX. Read it against GMO Aozora Net Bank for peer / contrast context and banking index for the broader system / regulatory boundary.

TL;DR

A former net bank that went through a dramatic parent-company switch: 2025-09-25 delisting from the TSE Standard market → 2025-10-01 becoming an NTT Docomo consolidated subsidiary → 2025-10-02 complete dissolution of the SBI HD capital relationship → 2026-08-03 planned rename to “Docomo SMTB Net Bank.” Having opened on 2007-09-24 as a 50:50 JV of Sumitomo Mitsui Trust + SBI HD, and after listing on 2023-03-29 PRIME, NTT Docomo acquired SBI HD’s stake just 2 and a half years later. With FY2024 (term 2025-03 ) consolidated net income of 281 億円, ordinary revenue of 1,465 億円, deposit balance of 9 兆 8,216 億円, and 825 万 accounts, it is the second-largest in the net-bank industry after rakuten-bank. Its core is the 2 -fold axis of being a No.1 -class net bank by mortgage origination volume plus one of Japan’s largest BaaS (NEOBANK) providers. It is a rare case where the bank that had been the backend of “docomo NEOBANK / d Smart Bank” was absorbed by its partner ndfg itself.

1. Company profile

Legal name: SBI Sumishin Net Bank, Ltd. (株式会社住信 SBI ネット銀行) → Docomo SMTB Net Bank, Ltd. (株式会社ドコモ SMTB ネット銀行) (rename planned for 2026-08-03) English name: SBI Sumishin Net Bank, Ltd. Securities code: former TSE STANDARD 7163 (delisted 2025-09-25; the former PRIME listing migrated in the Standard-market reorganisation of 2024 ) Established: 2007-09-24 (opened the same day) Current parents (from 2025-10-02):

• NTT Docomo: shareholding ratio 55.37% (under ndfg, consolidated subsidiary)
• Sumitomo Mitsui Trust Bank: shareholding ratio 44.63% (voting rights 50:50) Business type: net bank (ordinary banking licence) + BaaS provider Head office: Minato-ku, Tokyo Governance structure: company with a board of corporate auditors

Figures (FY2024 = term 2025-03 , consolidated basis)

Evolution of the capital relationship

At opening on 2007-09-24:
  Sumitomo Trust Bank 50% + SBI HD 50% (50:50  JV)

At PRIME listing on 2023-03-29:
  Sumitomo Mitsui Trust Bank approx. 35% + SBI HD approx. 35% + public shareholders approx. 30%

2025-09-25 delisting (NTT Docomo TOB completed)

2025-10-01 becoming an NTT Docomo consolidated subsidiary:
  NTT Docomo approx. 65.81% + Sumitomo Mitsui Trust approx. 34.19% (SBI HD stake acquired by NTT Docomo)

2025-10-02 capital reorganisation completed:
  SBI HD capital relationship fully dissolved

2026-08-03 rename + stake adjustment planned:
  NTT Docomo 55.37% + Sumitomo Mitsui Trust 44.63% (NTT Docomo sells 10.44% to Sumitomo Mitsui Trust)
  voting-rights ratio 50:50
  名name: "Docomo SMTB Net Bank, Ltd." (株式会社ドコモ SMTB ネット銀行)
  positioning: 1 社 among 4 社 under ndfg (2026-07-01 planned to be established)

Key chronology

2. Business-segment map

NEOBANK services (BaaS) list

SBI Sumishin Net Bank provides banking functions to other companies via API under the “NEOBANK” brand. Major partners:

NEOBANK is an API that lets operators (airlines / telecoms / retail / real estate / life insurers) provide banking functions (ordinary deposits, transfers, card loans, etc.) to their customers under their own brand. Sumishin SBI provides the banking licence + backend, with a design where the surface is completed within the operator’s app / brand.

Strategic implications of the parent-company switch (2025)

• NTT Docomo side: The motive for the acquisition was “to make up for being behind other telecom carriers in the banking business.” Establishing its own financial platform to compete with au Jibun Bank (KDDI affiliate) / PayPay Bank (SoftBank affiliate).
• SBI HD side: Recovering funds by selling the Sumishin SBI stake, and consolidating its retail strategy in SBI Shinsei Bank (the former Shinsei Bank).
• Sumitomo Mitsui Trust side: Its partner shifted from SBI HD to NTT Docomo. Management influence is unchanged, maintaining voting rights of 50:50 .

Core of differentiation

• Mortgage specialisation → the 2 -fold axis of BaaS expansion: In the early days of operation it captured real demand with mortgages (Flat 35 / variable), and in later years it cultivated BaaS as a 2 -th axis.
• BaaS is the biggest differentiator from other net banks: paypay-bank / rakuten-bank / au Jibun Bank centre on cross-selling within their own economic spheres, while Sumishin SBI follows an external-sales model.
• The new parent NTT Docomo economic sphere: After delisting, deepened linkage with d-Point and Docomo line customers 9,000 万 is anticipated.
• Sumitomo Mitsui Trust group backbone: Access to trust / pension / real-estate-trust functions is a strength that other net banks lack.

Partnership / acquisition strategy (from 2025-10 )

• NTT Docomo (new top shareholder): from 2025-10-01 a consolidated subsidiary, a core financial function under ndfg. docomo NEOBANK is promoted from “BaaS partnership” to “in-house banking service.”
• Sumitomo Mitsui Trust Bank (co-parent): a JV partner since establishment; provision of trust / pension infrastructure continues.
• SBI HD (capital relationship dissolved): 2025-10-02 fully dissolved. The future of the “hybrid deposit” with SBI Securities / the crypto-asset linkage API with SBI VC Trade is undetermined.
• Linkage with the former parent SBI group: How the existing API linkage with SBI Securities / SBI VC Trade will be continued / scaled back is at issue.

Competitive position (net-bank industry, from 2025-10 )

4. Regulation / policy

• Competent authority: Financial Services Agency (FSA)
• Licence: ordinary banking licence (Banking Act)
• 2025 TOB: NTT Docomo became the top shareholder after going through Article 52 -9 of the Banking Act (approval of a major bank shareholder) and prior notification under the Antimonopoly Act
• Crypto-asset linkage: The continuity of the API with SBI VC Trade after the dissolution of the SBI capital relationship is at issue.
• BaaS regulation: From 2022, the institutional arrangement of bank agency business / electronic payment intermediary business / authorised financial-instruments intermediary business, etc., is a continuing issue.
• Recent policy issues:
  • From 2024, normalisation of the BOJ’s policy interest rate → improvement in the deposit-loan margin
  • From 2024, expansion of NISA → accelerated fund inflows via online-brokerage linkage
  • From 2025, net-bank responses to the stablecoin regime (centred on megabank Progmat)

Related

• ndfg · smtb-hd · sbi-hd · rakuten-bank · paypay-bank
• mufg · smfg · mizuho-fg
• minna-bank-baas-model · mercari-bank-license-stack
• jp-crypto-exchange-overview

Sources

• Wikipedia: 住信 SBI ネット銀行 (https://ja.wikipedia.org/wiki/住信SBIネット銀行, extracted 2026-05-19)
• Wikipedia: NTT ドコモ (Sumishin SBI acquisition section, extracted 2026-05-19)
• SBI Sumishin Net Bank official IR (https://www.netbk.co.jp/contents/company/ir/, extracted 2026-05-19: delisting confirmed)
• SBI Holdings securities report (public materials)
• Sumitomo Mitsui Trust HD securities report (public materials)

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[!info] Verification status confidence: likely (v2.0 reflecting the parent-company switch 2026-05-19). FY2024 (term 2025-03 ) consolidated: ordinary revenue 1,465 億円, net income 281 億円, deposit balance 9.8 兆円, 825 万 accounts, and loans 8.7 兆円 are based on the earnings disclosure via Wikipedia; direct reference to the original earnings-report PDF has not been carried out. Capital-structure evolution: 2025-09-25 delisting, 2025-10-01 becoming an NTT Docomo consolidated subsidiary (65.81%), 2025-10-02 complete dissolution of SBI HD, and 2026-08-03 planned rename (NTT Docomo 55.37% / Sumitomo Mitsui Trust 44.63%) rely on the Wikipedia description; confirmation of the original TOB-result report has not been carried out. The NEOBANK partner list is the portion disclosed as of 2025 ; the count is over 10 社, maintaining the “one of Japan’s largest” wording.