(ANSA) - Milan, December 16 - Asset management giant BlackRock reached a 7.789% stake in Italy's largest phone company Telecom Italia (TI), the US-based investor said in a statement on Monday. BlackRock's statement shot down reports over the weekend that its stake had risen over a 10% threshold, which sparked alarm at the Italian market regulator Consob. Consob President Giuseppe Vegas blasted BlackRock for failing to comply with regulatory rules saying it had not providing communication on its growing stake, in an interview with newspaper Il Sole 24 Ore published Sunday. Vegas added that Consob was investigating. BlackRock's December 9 filing with the US market regulator SEC reported a 10.14% stake in TI, Vegas told Il Sole 24 Ore. BlackRock's confirmed stake still makes it the second largest single shareholder after Telco, a holding company controlled by the Spanish telecom company Telefonica which owns 22.39% of TI. Vegas said the last communication Consob had received was on October 2, when BlackRock reported it had broken the 5% threshold to reach a 5.13% stake. Telecom Italia on Monday said in a note that it had not received any notice of BlackRock's advancing ownership. Stock in Telecom Italia rose 4.9% to 0.69 euro per share on Monday. TI has speculative appeal, an analyst at Equita Telecom Italia wrote. Equita cited antitrust troubles in Argentina for TI's shareholder of reference Telefonica, Vegas's reported receptiveness to a takeover bid for TI by another major telecommunications company, and a possible shake up at a TI board meeting slated for December 20.