* Former CFO Carlo Ferro named as COO at ST-Ericsson

* STMicro gets new CFO (Adds, details)

PARIS, Feb 20 (Reuters) - Europe's biggest chip maker STMicroelectronics said it was sending its chief financial officer to be the chief operating officer of its stuggling mobile chip joint venture ST-Ericsson.

The move is a sign of how important the turnaround of ST-Ericsson, which has been hit hard by the loss of business from key customer Nokia, has become to its parent company.

Carlo Ferro will be COO of ST-Ericsson and report to Didier Lamouche, who was named a little more than a year ago to pilot the turnaround. Ferro is seen as someone with a strong experience in corporate restructuring, who knows the mobile chip business and supply chain issues well.

STMicro also on Monday named Mario Arlati to replace Ferro as chief financial officer.

Arlati was previously STMicroelectronics' chief accounting officer and head of corporate external reporting, the statement said.

STMicroelectronics shares were up 5.6 percent to 5.57 euros per share at 1056 GMT, making it the biggest gainer on France's blue chip index.

"The management change in our view underlines the commitment of STMicro to the ailing ST-Ericsson," wrote ING in a research note. "At the same time, it might lead to speculation on the next steps to turnaround ST-Ericsson which is the key swing factor in the STMicro investment case."

ST-Ericsson is a key supplier for Nokia's Symbian platform, which is now being phased out in favour of Microsoft Corp mobile software. It has been hit hard as the Finnish vendor loses out to Apple Inc and Google Inc in the smartphone market and by the abandon of Symbian.

ST-Ericsson has not won enough new deals to compensate for the major drop in business from Nokia and it posted a fourth-quarter net loss of $231 million compared with a $177 million loss in the year-ago quarter.

Lamouche, the head of ST-Ericsson, has promised to unveil his strategic plan to fix the mobile chip maker sometime in March.

(Reporting by Leila Abboud and Elena Berton; Editing by Jon Loades-Carter)

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