UPDATE 1-Frankie & Benny's owner Restaurant Group CEO steps down, shares sink

(Adds details, share movement, analyst quote)

Feb 14 (Reuters) - Frankie & Benny’s owner Restaurant Group Plc said on Thursday its Chief Executive Officer Andrew McCue was leaving the company, citing “extenuating personal circumstances,” sending its shares tumbling as much as 13 percent.

Restaurant Group did not elaborate further on the circumstances of its CEO’s departure, but said his exit was not related to the company’s business.

“While I recognise that this decision is untimely, it is the right one for me and my family,” McCue said in a statement.

McCue is expected to remain in his position until a successor is found, the company said.

“The timing of this announcement comes as a surprise given the recent £559m acquisition of Wagamama and comes during the crucial stage of integration to deliver £22m synergies promised, adding further instability and risk,” Liberum said in a note.

The company, which operates over 650 restaurants and pub restaurants throughout the UK, bought Wagamama noodle chain in October, while nearly 40 percent of shareholders had opposed the deal.

Shares of the company were trading down 11 percent at 129.96 pence by 0907 GMT, after touching a low of 127 pence. They halved in value since McCue became CEO in September 2016. (Reporting by Samantha Machado and and Sangameswaran S. in Bengaluru; Editing by Gopakumar Warrier)