NEW YORK (TheStreet) - Fortinet (FTNT) - Get Report shares tanked almost 10% in pre-market trading on Friday following the surprise resignation of the company's CFO Ahmed Rubaie.

In a statement released after market close on Nov.27, Fortinet said that Rubaie is leaving the company "for personal reasons". Rubaie, who has been with the security specialist for just seven months, will remain employed with Fortinet until Dec.5. He will also be available "on a reasonable basis" through March 5, 2014, to assist with the CFO transition. Nancy Bush, Fortinet's vice president and worldwide corporate controller, will serve as interim CFO.

Fortinet shares plunged 9.62% to $17.75 before market open.

Apple (AAPL) - Get Report, which is touting gift cards for its annual Black Friday promotion, gained 0.73% to $549.97. The iPad maker was also one of the most active pre-market Nasdaq stocks on share volume of 210,174. Facebook (FB) - Get Report was another gainer, rising 0.3% to $46.63 on share volume of 159,014.

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SiriusXM (SIRI) - Get Report shares gained 0.14% to $3.69 on share volume of 113,987.

Over at the NYSE, however, HP (HPQ) - Get Report was a laggard, slipping 1.02% to $27.08 as investors continue to digest the PC maker's fourth-quarter results earlier this week.

--Written by James Rogers in New York.

Follow @jamesjrogers

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