Darktrace PLC (LON:DARK) shares jumped by 40% in early trades after the price of the float was halved from initial estimates.
Shares in the cybersecurity group were changing hands at 359p as dealings started after the float was priced at 250p per share or £1.7bn.
When the British tech first announced it would float on 19 April, valuations had gone as high as £3.6bn but signs that it was proving a struggle to get away came last week with reports the price had been cut to between £2.4-2.7bn.
The disastrous recent float of Deliveroo, which slumped after being shunned by a raft of high profile institutional investors and also the presence of controversial Autonomy founder Mike Lynch as a backer were said to reasons investors were being cautious.
Poppy Gustafsson, Darktrace's chief executive, said: "This milestone marks an exciting day for Darktrace. This business is one built by collaboration and as such there are many people I would like to thank.
"Our company is deeply rooted in the UK's tradition of scientific and mathematic research so we are especially proud to be listing on the London Stock Exchange."
-adds share price--