And they all contained sensitive work data, found EE.
Ten million smartphones, tablets and laptops containing sensitive business data were lost by employees last year, according to EE.
The telecom company’s study of 2,000 Brits found that one in five had lost a mobile device on a work night out, while one in six owned up to leaving their device on public transport.
EE claimed that business data is becoming more sensitive on mobile devices due to the availability of 4G increasing their use for work tasks, and so has launched a business portfolio to secure smartphones and tablets.
The firm said its Super Secure 4GEE portfolio provides businesses with the tools to securely manage access to company data such as email and business applications like SAP and Office, as well as other content.
Gerry McQuade, CMO for business at EE, said: "More often than not, employees will use their personal mobile device to access company emails, documents or presentations, unaware that they may be putting sensitive data at risk. What’s important is that business data is secure, whether accessed from a company-owned device or not.
"With the arrival of 4G, businesses of all sizes now have an opportunity to become genuinely mobile by giving their employees secure access to company information and business applications regardless of the device they’re using and the operating system the device is running."
The news comes after analyst house Quocirca conducted research with Oracle to find that half of European and UK businesses are not including smartphones in their BYOD strategies.
The survey of 700 companies found that 37% were not aware of containerisation, the process of separating company and personal data on a device.
EE’s offering is available in different forms for small, medium and large businesses, and covers containerisation as well as the ability to remotely lock or wipe devices.