Alphabet's Google LLC convinced a US appeals court to cancel three anti-malware patents at the heart of a Texas jury's $20-million infringement verdict against the company.

The US Court of Appeals for the Federal Circuit says that Alfonso Cioffi and Allen Rozman's patents were invalid because they contained inventions that were not included in an earlier version of the patent.

Cioffi and the late Rozman's daughters sued Google in East Texas federal court in 2013, alleging anti-malware functions in Google's Chrome web browser infringed their patents for technology that prevents malware from accessing critical files on a computer.

A jury decided in 2017 that Google infringed the patents and awarded the plaintiffs $20 million plus ongoing royalties, which their attorney said at the time, were expected to total about $7 million per year for the next nine years.

But the Federal Circuit says that all of the patents were invalid. The three patents were reissued from an earlier anti-malware patent, and federal law required the new patents to cover the same invention as the first, the unanimous three-judge panel concluded.

Alphabet Inc shares fell as much as four percent following a report South Korea's Samsung Electronics was considering replacing Google with Microsoft-owned Bing as the default search engine on its devices.

Google's reaction to the threat was ‘panic’ as the company earns an estimated $3 billion in annual revenue from the Samsung contract, the report said, citing internal messages.

According to the company, it was working to bring new AI-powered features to Search without commenting on its association with Samsung.