Shares in sat-nav firms TomTom and Garmin plummeted on Wednesday, after Google announced free turn-by-turn navigation software for Android 2.0 handsets.
Google unveiled the beta version of Google Maps Navigation as Verizon and Motorola launched the Droid phone, the first handset to use the 'Eclair' version of the Android mobile operating system, in the United States.
The software — currently only of use to US drivers — provides 3D views, search by voice, turn-by-turn voice guidance and automatic rerouting.
By late afternoon, UK time, TomTom's shares had fallen by 21.9 percent. Garmin's shares were down 17.6 percent.
On Tuesday, Google updated the Android software development kit to take advantage of new features in the Eclair revision. These enhancements include native multitouch, Exchange support and HTML 5 support.