Amazon Web Services and Standard Chartered Bank are making it official.

London-based Standard Chartered has inked a five-year agreement with AWS, which includes the bank running its core systems and customer-facing applications on the cloud platform.

The new deal is part of SC’s multicloud strategy, and builds on SC’s multiyear partnership with Microsoft Azure that was announced in August. The goal is for all SC’s core banking and trading systems, client channels and new digital ventures — including virtual banking and banking-as-a-service — to be cloud based by 2025.

The migration, along with taking a cloud-first approach to all new software developments, is anticipated to reduce technology infrastructure costs by at least 20%, Bhupendra Warathe, SC’s chief technology officer of cloud transformation, told Bank Innovation.

SC was already leveraging AWS’ services prior to the Nov. 11 announcement. The $754 billion dollar bank used AWS to launch Mox, its virtual bank in Hong Kong, in September, and nexus, its banking-as-a-service solution, in March. Meanwhile, SC’s financial market business, which includes risk management, financing and investment services, uses AWS to run algorithms and assess market risk, and is looking to Amazon Elastic Compute Cloud to scale up those workloads during peak demand. The bank also uses Amazon Aurora to run its global payments system and core banking system. Amazon Aurora is a relational database used to store details of banking and e-commerce transactions for the faster and more secure transfer of funds.

Some bank systems won’t make it to the cloud, however. Applications running on the bank’s mainframe systems will run on premises until end of life, Warathe added. SC operates two on-prem data centers for hosting applications — one in Asia and the other in Europe — and its public cloud strategy will straddle four regions: Hong Kong, Singapore, the U.K. and Ireland.

By decentralizing applications across regions and “availability zones,” a term used for specific, isolated locations in which cloud providers segment their data centers, SC is hoping to make its systems operationally resilient, Warathe said. Pairing regions — like Hong Kong and Singapore, and the U.K. and Ireland — allows SC to achieve cross-regional continuity, so if AWS Hong Kong systems were to fail, AWS Singapore systems could recover the processing load.

Portability of applications, or the ability for software to be transferred from one machine to another, is another important aspect of the partnership. “The target is to have the right application architecture so that we can achieve cross-CSP [cloud service provider] portability within three to six months,” Warathe said.

AWS and Microsoft Azure dominate the financial services market in the U.S., Europe, the Middle East and Africa, according to data from 451 Research, a subsidiary of S&P Global Market Intelligence. A 2019 market snapshot showed 90% of financial institutions use AWS and Azure as their primary cloud providers. AWS offers more than 175 services across compute, storage, analytics, robotics, machine learning, AI, and application development, deployment and management from 77 availability zones, and has plans to add 15 more availability zones and five geographic regions for a total of 29 regions.