The Singapore Exchange SGX, London-based Aquis Exchange and Amazon Web Services said they undertook a proof of concept to show that trading shares in the cloud can be sufficiently fast and reliable.

"It's proven to be technically capable," said Adrian Ip, a director at Aquis Exchange's technology arm.

Exchanges using the cloud to date for trading are limited in size or niche, such as dealing in crypto assets, Ip said.

Amazon's move into "multicast" or an ability to send data to many parties at the same time in the cloud, a key requirement for any exchange of size, was a breakthrough, Ip said.

Despite exchanges spending millions of dollars on physical back-up servers, there have been outages this year in Japan, Australia, and at Euronext in Europe, drawing close scrutiny from regulators.

A cloud-based exchange could be more resilient than relying on physical infrastructure dotted across regions, Ip said.

Mayumi Hiramatsu, Vice President at Amazon Web Services, said the pilot showed a path to free up customers from maintaining legacy on-premises infrastructure.

Aquis and SGX are looking at how to take forward findings from their pilot with Amazon, which they say could bring savings of up to 90%.

"We will be looking at how this can be scaled globally. We will take a considered and measured approach and discuss with regulators and members," Ip said.

It comes at a time when regulators globally are also taking a harder look at how financial firms are increasingly relying on third party cloud providers like Amazon, Google and Microsoft for critical services.

The European Union aims to be the first to introduce new laws to regulate such use of the cloud.

(Reporting by Huw Jones; Editing by Kirsten Donovan)

By Huw Jones