Nokia offers $8.1 billion for Navteq

The acquisition would give the world's top cellphone maker -- which is looking for new revenue sources as the cellphone industry matures -- a stronghold in the navigation business, one of the fastest growing segments in the technology industry.

Nokia shares fell 4.2 percent to 25.55 euros by 8:48 a.m. EDT, to be the biggest European blue-chip loser.

"It looks expensive," said OKO Bank analyst Hannu Rauhala.

Nokia said it would finance the deal with cash and debt. It had in cash and other liquid assets 8.3 billion euros at end-June.

Navteq has been seen as a takeover target since TomTom, the world's top maker of car navigation devices, offered 1.8 billion euros ($2.55 billion) in July for Navteq's only big rival, Tele Atlas.

Nokia bought into the navigation industry last year when it acquired German software firm Gate5, which uses map data from providers like Tele Atlas and Navteq

Nokia credit default swaps are 2 basis points wider at 22.5 basis points, according to Deutsche Bank prices, meaning it costs 22,500 euros a year to insure 10 million euros of Nokia debt against default.