Shares in Sophos, one of the UK's few tech "unicorns", launched its IPO today, valuing it at £1.01bn.
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Shares in the cyber security giant began conditional trading at 225p each this morning, raising $125m (£79.3m), with an over-allotment option that could net it another £52.8m.
The Oxford-based company is among the exclusive ranks of UK-based companies valued at more than $1bn (£634m), which include the likes of Zoopla, TransferWise, Just Eat and Asos.
Today's flotation represents the culmination of long-held IPO ambitions for Sophos. In 2007, it cancelled plans to list when the credit crunch hit, while in 2009, having investigated the idea, it decided instead to sell a majority stake to Apax.
Kris Hagerman, Sophos' chief executive, said the IPO marked a "significant milestone".
"We are proud to be part of Britain's growing tech economy as a listed business and a leading global provider in the cyber security sector."