The billionaire Patrick Drahi will not be forced to cut his stake in BT after the UK government ruled the investment did not pose any national security concerns. The entrepreneur, who moved to France as a teenager and holds Israeli, French and Portuguese citizenships, is BT’s biggest shareholder and has previously pursued debt-fuelled deals to buy assets in France, the US, Portugal and Israel. Drahi bought 12.1% of BT last year before his investment group Altice increased its holding to 18% at a cost of about £2.2bn. BT’s share price rose by 1.8% on Tuesday morning after it announced the government’s decision. Shares had fallen after the the announcement of a government investigation. Drahi, who has a net worth of $7bn (£5.9bn), according to the Bloomberg billionaires index, built his empire by developing and selling a series of telecoms companies. He founded Altice in 2001, taking on debt to fund acquisitions across Europe and then the US. However, he is perhaps better known in the UK for his $3.7bn purchase of the Sotheby’s in 2019. Drahi said he bought the auction house “with my family” – he is an art collector who is thought to own works by Picasso and Matisse. Drahi’s investment had prompted speculation over his intentions for the business, although he is yet to detail his strategy in public. The government decision to wave through his investment could open the way for further increases in the size of his stake, although the government made clear on Tuesday it would be able to assess “any future transaction”. Nevertheless, the decision removes one source of uncertainty hanging over BT, which is also facing strikes from thousands of workers hoping to win higher pay. Engineers at broadband infrastructure subsidiary Openreach and call centre workers at BT who are members of the Communication Workers Union, will take strike action on Tuesday and Wednesday next week. Drahi’s investment in BT prompted scrutiny by the government under new powers to intervene in takeovers of companies with interests in critical sectors of the UK economy, such as communications, energy, defence and transport. BT controls much of the UK’s fibre broadband network, and the government in May said it would “call in” the deal to investigate any threat to national security. “BT Group has now been notified by the secretary of state that no further action is to be taken,” BT said, referring to Altice. The business department said in a statement: “Following careful consideration, the government will take no further action on the acquisition of 5.9% shares by Altice in BT.”