Nuance Communications thinks of itself as the Switzerland of the ultra-competitive technology industry. Smartphone rivals Samsung, Apple and BlackBerry use its voice-control technology to power their virtual assistants, as do carmakers including Volkswagen, Ford and BMW.

"Nuance over the years has just evolved to be very successful at that and we treat each partner uniquely," says Paul Ricci, Nuance's chief executive of 13 years.

However, Mr Ricci is about to experience a different relationship, one in which he might find it harder to be neutral. Carl Icahn, an activist investor, has been building a stake in Nuance since April, and last week made a financial filing that signalled an intention to move from a passive to activist position in the company. – Copyright The Financial Times Limited 2013