Judged by what they disclose about cloud migration, core-banking modernisation and APIs, the large banks with the most evidence of a modern stack are Arvest, Texas Capital, Deutsche Bank, Citizens and Central Bank: Arvest (Cloud migration timeline: ≈ 2.5 years in; completion slated for 2027 (Sep 9, 2024); Time to build first…); Texas Capital (Processes mapped for firm-wide agents / internal APIs: > 170 / > 250 (Apr 23, 2026); Critical infrastructure…); Deutsche Bank (Private Bank targets: KYC manual handling time / mortgage handling time / core platforms / inquiries…); Citizens (Applications migrated to cloud: 700 in four years (Jun 1, 2026); Cloud move results: 25 data centres closed…); Central Bank (Core modernisation spend capitalised to date: $12 million (Jun 30, 2026); Core modernisation spend…). 36 of the 140 profiled banks have published a number for cloud, core or API modernisation; 74 more have dated a move without a figure; 30 disclose nothing on the subject.
Data as of Oct 6, 2026 · 140 banks profiled (120 US, 20 non-US) · 110 with evidence on this topic · 79 sources cited below · ranked answer, not a comparison
Which banks disclose the most about modernising their stack?
The 30 highest of 110 banks with any cloud, core-banking, data-centre, API or legacy-modernisation evidence on their page. Columns: the disclosed numbers, the latest dated move, the evidence counts behind the score, and the score. Status reads the latest move: a completed step (migration finished, data centres closed, core live) or work in progress.
| # | Bank | Disclosed cloud / core / API numbers | Latest modernisation move | Evidence | Score | Status | Date | Sources |
|---|---|---|---|---|---|---|---|---|
| 1 | Arvest | Cloud migration timeline: ≈ 2.5 years in; completion slated for 2027 (Sep 9, 2024); Time to build first product on the new core: < 9 months (live October 2022) (Feb 23, 2023) | Jennifer Baker named chief information officer (Dec 3, 2025) | 5 numbers · 7 moves · 5 use cases | 23 | In progress | Dec 3, 2025 | American Banker ↗ · Arvest Bank (PR Newswire) ↗ · Bank Automation News ↗ |
| 2 | Texas Capital | Processes mapped for firm-wide agents / internal APIs: > 170 / > 250 (Apr 23, 2026); Critical infrastructure in the cloud: 96% (Oct 23, 2025) | AWS publishes Texas Capital's 'Trust-Earned Autonomy' agent demonstration (Oct 5, 2026) | 4 numbers · 4 moves · 6 use cases | 19 | In progress | Oct 5, 2026 | The Motley Fool (Yahoo Finance) ↗ · Texas Capital ↗ · Amazon Web Services (AWS Industries blog, according to AWS) ↗ |
| 3 | Deutsche Bank | Private Bank targets: KYC manual handling time / mortgage handling time / core platforms / inquiries AI-assisted: -30% / -60% / 15 to 2 / more than 80% (Nov 17, 2025); Corporate Bank 2028 indicators: AI-enabled core processing systems / fewer applications / client straight-through processing / applications on cloud: 100% / about -20% / +40% / +30 percentage points (Nov 17, 2025) | Agentic resilience platform for DORA exercises (Aug 18, 2026) | 3 numbers · 5 moves · 1 use cases | 15 | In progress | Aug 18, 2026 | Deutsche Bank ↗ · Deutsche Bank ↗ · Deutsche Bank ↗ |
| 4 | Citizens | Applications migrated to cloud: 700 in four years (Jun 1, 2026); Cloud move results: 25 data centres closed; infrastructure cost −10% to −15%; incidents −78%; ≈ $45 million annualised savings (Jun 1, 2026) | The mainframe goes: CIO's cloud-first claim (Jun 1, 2026) | 2 numbers · 7 moves · 3 use cases | 14 | Completed step | Jun 1, 2026 | American Banker ↗ · American Banker ↗ · American Banker ↗ |
| 5 | Central Bank | Core modernisation spend capitalised to date: $12 million (Jun 30, 2026); Core modernisation spend capitalised in Q1 2026: ≈ $700,000 (Mar 31, 2026) | Q2 2026 10-Q: $12 million of core modernisation capitalised (Aug 14, 2026) | 2 numbers · 8 moves · 4 use cases | 14 | In progress | Aug 14, 2026 | Central Bancompany (SEC filings) ↗ · earnings call transcript (The Motley Fool) ↗ · Central Bancompany (SEC filings) ↗ |
| 6 | BankUnited | Software and cloud-computing arrangements, gross cost: $121.8 million (2024: $116.1 million) (Dec 31, 2025); SAVI accuracy and response time (undated AWS case study): 95% and under 10 seconds, across about 400 policy documents (Sep 24, 2026) | Q2 2026 call: staying out of data-centre lending (Jul 22, 2026) | 2 numbers · 4 moves · 4 use cases | 13 | In progress | Sep 24, 2026 | SEC EDGAR ↗ · Amazon Web Services ↗ · Yahoo Finance ↗ |
| 7 | Commonwealth Bank | Data pipelines migrated to AWS; AI models; data points; daily AI decisions: over 61,000 pipelines; over 2,000 models; about 157 billion data points; about 55 million decisions a day (Jun 4, 2025); Customers and accounts moved to the AWS-hosted core banking platform: 17 million customers; 28 million accounts (Jun 30, 2026) | San Francisco Technology Hub opens (May 13, 2026) | 2 numbers · 6 moves · 2 use cases | 13 | In progress | Jun 30, 2026 | Commonwealth Bank of Australia ↗ · Commonwealth Bank of Australia ↗ · Commonwealth Bank of Australia ↗ |
| 8 | Popular | Increase in 2025 technology and software expenses tied to cloud infrastructure: $12.5 million (Dec 31, 2025); Amortisation of cloud computing arrangements, first half of 2026: $7.6 million (first half 2025: $2.8 million) (Jun 30, 2026) | Q2 2026 Form 10-Q: technology and software expenses $91.0 million (Aug 7, 2026) | 2 numbers · 5 moves · 1 use cases | 12 | In progress | Aug 7, 2026 | Popular, Inc. (SEC filings) ↗ · Popular, Inc. (SEC filings) ↗ · IBM ↗ |
| 9 | State Street | Applications on modern cloud platforms: ~40% today; target ~80% (Jul 16, 2026) | Christopher Herringshaw hired as global chief technology officer (Aug 4, 2026) | 1 numbers · 5 moves · 3 use cases | 11 | In progress | Aug 4, 2026 | State Street (SEC filing) ↗ · FinTech Futures ↗ · Motley Fool (Yahoo Finance) ↗ |
| 10 | HSBC USA | Google Cloud programme: 200+ use cases in two years; projects each > $100 million (Jun 17, 2026); HSBC applications already on Google Cloud / transactions monitored for financial crime (group): 600+ / nearly 1 billion a month (Jun 17, 2026) | Google Cloud partnership (Jun 17, 2026) | 2 numbers · 1 moves · 3 use cases | 10 | In progress | Jun 17, 2026 | Bloomberg ↗ · Google Cloud (PR Newswire) ↗ · PYMNTS ↗ |
| 11 | MUFG | Expected system-development effort per branch-procedure standardisation with AI Flowchart (according to AWS): 11 person-days to 1 (up to 90% less); individual flowchart creation down 95% (Oct 8, 2026) | AWS: AI Flowchart cuts branch-procedure standardisation work (Oct 8, 2026) | 1 numbers · 4 moves · 3 use cases | 10 | In progress | Oct 8, 2026 | Amazon Web Services (AWS Database Blog) ↗ · Mitsubishi UFJ Financial Group, Inc. ↗ · Mitsubishi UFJ Financial Group, Inc. ↗ |
| 12 | Zions | Speed-up for products relying on the new core: 20% faster (Sep 24, 2025); Deposit products after the core replacement: ≈ 100, from ≈ 500 (Aug 21, 2024) | Q1 2026 call: CEO on AI use cases and the agentic-AI threat (Apr 20, 2026) | 2 numbers · 3 moves · 0 use cases | 9 | In progress | Apr 20, 2026 | American Banker ↗ · American Banker ↗ · Yahoo Finance ↗ |
| 13 | Flagstar | Data centres consolidated: 6 → 2 colocation centres (Ashburn and Chicago), in about one year (Jun 30, 2026) | Inside StarIQ: who uses it and how it is governed (Jul 30, 2026) | 1 numbers · 6 moves · 1 use cases | 9 | In progress | Jul 30, 2026 | American Banker ↗ · Yahoo Finance ↗ · American Banker ↗ |
| 14 | Prosperity | Post-weekend account update time after core conversion: ≈ 1.5 hours (Apr 29, 2026) | First-quarter 2026 results (Apr 29, 2026) | 1 numbers · 3 moves · 2 use cases | 8 | Completed step | Apr 29, 2026 | Earnings call transcript (The Motley Fool) ↗ · Prosperity Bancshares ↗ · Prosperity Bank ↗ |
| 15 | Deutsche Bank (U.S.) | Core banking platforms: 15 → 2 (Nov 17, 2025) | Investor Deep Dive sets 2028 AI targets (Nov 17, 2025) | 1 numbers · 4 moves · 1 use cases | 8 | In progress | Nov 17, 2025 | Deutsche Bank ↗ · Deutsche Bank ↗ · Deutsche Bank ↗ |
| 16 | Commerce | no cloud, core or API number disclosed | Second-quarter release carries no AI language (Jul 16, 2026) | 0 numbers · 6 moves · 3 use cases | 8 | In progress | Jul 16, 2026 | Commerce Bancshares ↗ · Commerce Bancshares ↗ · Commerce Bancshares ↗ |
| 17 | DBS | AI-related financing originated: About SGD 25 billion (USD 20 billion) in 2026 to 12 October, mostly hardware and data centres; only a fraction held (Oct 12, 2026) | Tan: AI pace may force a resiliency versus speed trade-off (Aug 19, 2026) | 1 numbers · 3 moves · 2 use cases | 8 | In progress | Oct 12, 2026 | The Business Times (Bloomberg) ↗ · Yahoo Finance (syndicated report of the Singapore Computer Society Tech3 Forum) ↗ · Computer Weekly ↗ |
| 18 | NatWest | no cloud, core or API number disclosed | First UK bank with an app in ChatGPT (Apr 30, 2026) | 0 numbers · 6 moves · 4 use cases | 8 | In progress | Apr 30, 2026 | NatWest Group ↗ |
| 19 | PNC | no cloud, core or API number disclosed | Barclays conference: agents at the centre of development, 5–10x (Sep 14, 2026) | 0 numbers · 5 moves · 2 use cases | 7 | In progress | Sep 14, 2026 | Investing.com ↗ |
| 20 | BNY | no cloud, core or API number disclosed | CFO: ~$4 billion annual engineering spend funds Eliza; expense outlook raised partly on AI (Sep 19, 2026) | 0 numbers · 5 moves · 2 use cases | 7 | Completed step | Sep 19, 2026 | Yahoo Finance ↗ · The Wall Street Journal ↗ · Banking Dive ↗ |
| 21 | Glacier | Guaranty (Texas) loan growth in Q1 2026, the quarter of its core conversion: More than 6% (Apr 24, 2026) | Q2 2026 10-Q repeats the AI risk language (Aug 4, 2026) | 1 numbers · 3 moves · 1 use cases | 7 | In progress | Aug 4, 2026 | earnings call transcript (The Motley Fool) ↗ · Glacier Bancorp (SEC filings) ↗ · American Banker ↗ |
| 22 | Customers Bank | Target cubiX agentic-interface client API requests by year-end 2026: Nearly 2 billion (Jul 23, 2026) | Q2 2026 deck: 46,000 hours, 600 agents, 100% licensed (Jul 23, 2026) | 1 numbers · 2 moves · 2 use cases | 7 | In progress | Jul 23, 2026 | Customers Bancorp (SEC filings) ↗ · Customers Bancorp (Business Wire via Morningstar) ↗ |
| 23 | TowneBank | no cloud, core or API number disclosed | Dogwood core-systems conversion scheduled for November 2026 (Jan 12, 2026) | 0 numbers · 4 moves · 3 use cases | 7 | In progress | Jan 12, 2026 | TowneBank ↗ · TowneBank (from The CEO Magazine) ↗ · Talkdesk ↗ |
| 24 | Lloyds | Engineers on GitHub Copilot: More than 11,000; about 50% less legacy code conversion time (Jul 30, 2026) | 800 AI models live and Copilot for all colleagues planned (Jul 30, 2026) | 1 numbers · 3 moves · 1 use cases | 7 | Completed step | Jul 30, 2026 | Lloyds Banking Group ↗ · PYMNTS ↗ · Google Cloud ↗ |
| 25 | Huntington | Documents redacted with AWS ML pipeline: 400 million+; ≈ 10 million a day; cost ≈ 5% of original estimate; accuracy > 95% (Jun 24, 2026) | 400 million documents redacted with AWS machine learning (Jun 24, 2026) | 1 numbers · 3 moves · 0 use cases | 6 | In progress | Jun 24, 2026 | AWS Machine Learning Blog ↗ |
| 26 | Amex | no cloud, core or API number disclosed | Intent Intelligence framework published (Oct 13, 2026) | 0 numbers · 3 moves · 3 use cases | 6 | In progress | Oct 13, 2026 | American Express via FT Markets ↗ · TechCrunch ↗ · Motley Fool (Yahoo Finance) ↗ |
| 27 | Ally | no cloud, core or API number disclosed | 2025 10-K adds a stand-alone AI risk factor (Feb 25, 2026) | 0 numbers · 5 moves · 1 use cases | 6 | In progress | Feb 25, 2026 | Ally Financial (SEC filings) ↗ · Bandwidth (PR Newswire) ↗ |
| 28 | Frost | Tier-one capabilities modernised: 66% (40% in the cloud); target 91% in 2027 (Aug 17, 2026) | Investor deck names a contact-centre copilot (Aug 17, 2026) | 1 numbers · 2 moves · 1 use cases | 6 | In progress | Aug 17, 2026 | Cullen/Frost Bankers (SEC filings) ↗ |
| 29 | Beacon Bank | no cloud, core or API number disclosed | First-quarter call: conversion done, merger costs at $93 million (Apr 30, 2026) | 0 numbers · 4 moves · 2 use cases | 6 | Completed step | Apr 30, 2026 | earnings call transcript (The Motley Fool) ↗ · Beacon Financial (GlobeNewswire) ↗ · Beacon Financial (PR Newswire) ↗ |
| 30 | Trustmark | Age of replaced core system: 45 years (Jul 28, 2026) | Second-quarter 2026 results; core conversion complete (Jul 28, 2026) | 1 numbers · 2 moves · 1 use cases | 6 | Completed step | Jul 28, 2026 | StockStory (Yahoo Finance) ↗ · Trustmark Corporation (Business Wire via Yahoo Finance) ↗ · Investing.com ↗ |
Each row quotes the bank's page on this site; the bank link opens the full record with every source. “Not disclosed” means the page records nothing on that point. Banks absent from the table have no evidence on this topic on their page.
Which banks lead on stack modernisation within each size tier?
The same ranking within size tiers; the headline is the first disclosed number, or the latest move where there is none.
| Tier | Overall rank | Bank | Headline evidence |
|---|---|---|---|
| US banks over $500bn | #19 | PNC | Barclays conference: agents at the centre of development, 5–10x (Sep 14, 2026) |
| US banks, $100bn to $500bn | #4 | Citizens | Applications migrated to cloud: 700 in four years (Jun 1, 2026); Cloud move results: 25 data centres closed… |
| US banks, $100bn to $500bn | #9 | State Street | Applications on modern cloud platforms: ~40% today; target ~80% (Jul 16, 2026) |
| US banks, $100bn to $500bn | #10 | HSBC USA | Google Cloud programme: 200+ use cases in two years; projects each > $100 million (Jun 17, 2026); HSBC applications… |
| US banks, $100bn to $500bn | #20 | BNY | CFO: ~$4 billion annual engineering spend funds Eliza; expense outlook raised partly on AI (Sep 19, 2026) |
| US banks under $100bn | #1 | Arvest | Cloud migration timeline: ≈ 2.5 years in; completion slated for 2027 (Sep 9, 2024); Time to build first product on the… |
| US banks under $100bn | #2 | Texas Capital | Processes mapped for firm-wide agents / internal APIs: > 170 / > 250 (Apr 23, 2026); Critical infrastructure in the… |
| US banks under $100bn | #5 | Central Bank | Core modernisation spend capitalised to date: $12 million (Jun 30, 2026); Core modernisation spend capitalised in Q1… |
| US banks under $100bn | #6 | BankUnited | Software and cloud-computing arrangements, gross cost: $121.8 million (2024: $116.1 million) (Dec 31, 2025); SAVI… |
| Non-US banking groups | #3 | Deutsche Bank | Private Bank targets: KYC manual handling time / mortgage handling time / core platforms / inquiries AI-assisted: -30%… |
| Non-US banking groups | #7 | Commonwealth Bank | Data pipelines migrated to AWS; AI models; data points; daily AI decisions: over 61,000 pipelines; over 2,000 models… |
| Non-US banking groups | #11 | MUFG | Expected system-development effort per branch-procedure standardisation with AI Flowchart (according to AWS): 11… |
| Non-US banking groups | #17 | DBS | AI-related financing originated: About SGD 25 billion (USD 20 billion) in 2026 to 12 October, mostly hardware and data… |
How is this ranking computed?
Score = 3 × disclosed numbers whose label or value mentions cloud, a core-banking system, data centres, mainframes, APIs, microservices or legacy modernisation, + dated timeline moves on the same subjects (capped at 5) + use cases on the same subjects (capped at 3). Ties by assets. Only entries already on the bank's page count; each is sourced there.
Status is read from the latest move's wording (completed, closed, migrated, live versus announced or underway) and is a reading, not a disclosure.
What are the caveats?
"Modern" here means disclosed modernisation. A bank that finished its cloud migration years ago and stopped talking about it scores below one that is mid-migration and reporting progress. Capital One, which says it closed its last data centre in 2021, is the clearest example of an early mover whose evidence is now dated.
The percentages and counts banks publish (applications on cloud, data centres closed, core products consolidated) use different bases and are not comparable across banks.
How does this differ from the AI index?
The AI index has no technology-stack component; this page is built from the cloud, core and API entries on the bank pages, which the index counts only as generic numbers and moves. The AI index and its method are on their own page; the technology leaders and generative AI guides are hand-written cross-bank tables with their own sourcing.
Which large bank has the most modern technology stack?
By disclosure, Arvest Bank: Cloud migration timeline: ≈ 2.5 years in; completion slated for 2027 (Sep 9, 2024); Time to build first product on the new core: < 9 months (live October 2022) (Feb 23, 2023). No bank publishes a full architecture, so this is the best-evidenced, not the proven-best, stack.
Which banks have moved to the cloud?
Banks with a disclosed cloud figure include Arvest, Texas Capital, Deutsche Bank, Citizens and BankUnited; the number and date are in the table.
Which banks have replaced their core banking system?
Banks whose page dates a core conversion or replacement include Arvest, Deutsche Bank, Central Bank, Commonwealth Bank and Zions.
Why is the score not a percentage of cloud adoption?
Because only a few banks disclose one, and on different bases (applications, workloads, infrastructure, capacity). The score counts sourced evidence instead and shows each figure as reported.
Does a modern stack mean the bank leads in AI?
It helps: the banks that report the deepest AI adoption tend to be those that have moved data and applications to the cloud. But the AI leaders page and this one rank different evidence and disagree in places.
How many banks disclose nothing about their stack?
30 of 140; they are not in the table.
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