Loss-making mobile chip venture ST-Ericsson said on Monday its operations chief Didier Lamouche would replace its Chief Executive Gilles Delfassy from the start of December.

Lamouche will be the third chief executive for the 50:50 venture of Swedish group Ericsson and French STMicro, which has never made a quarterly profit and has been cutting costs since it was formed in 2009.

Lamouche joined the company earlier this year after five years as chief executive of French IT firm Bull. He has worked for years at IBM's semiconductor business and headed Altis Semiconductor, a venture of IBM and Infineon.

ST-Ericsson, a key supplier to Nokia's Symbian platform, has been hit hard by the Finnish vendor losing out to Apple and Google on the smartphone market and earlier this year deciding to swap Symbian for Microsoft software.

The venture has not been able to win enough new deals to compensate for the major missing business from Nokia.

The company now enters a phase with prime focus on proliferating design-wins and scaling up and delivering volume, with the objective of translating its new portfolio into sustainable profitability and growth, ST-Ericsson said in a statement.

After Ericsson last month agreed to sell its half in a similar cellphone venture Sony Ericsson, several analysts and commentators had been expecting it to exit from ST-Ericsson too, but both parents on Monday reiterated their commitment to the venture.

(Reporting by Tarmo Virki and Helena Soderpalm; Editing by Helen Massy-Beresford)