A group of former executives and investors from antivirus software maker AVG Technologies (AVG.N) is raising a $125 million fund to tap into opportunities in the booming cyber security sector, a founding partner in the fund said. With the size and scope of cyber attacks on companies growing in recent years, the security industry has seen a steady rise in financing deals and a market that research firm Gartner estimates will grow by 8 percent in 2015 to $77 billion.