Existing shareholders, who will retain a 43.2 per cent stake in the company, sold 26.3 million shares, taking the total offer size to $99 million.
The $2.40 issue price gave Gentrack a market capitalisation of $174.5 million.
Gentrack chairman John Clifford said the offer attracted strong support from institutional and retail investors.
"Investors clearly understand the attributes and position of Gentrack's solutions for utilities and airports on the domestic and international stage, backed by the proven capabilities of its staff and management team to deliver profitable growth," Clifford said. "We are delighted to welcome as investors institutions in New Zealand and Australia and eligible retail investors in the UK, New Zealand and Australia."
Read also:
*Stock Takes: PowerbyProxi talks set scene for market listing
*Stock Takes: Profit vs. growth in tech IPOs
*'Boycott' sinks Hirepool float
*Serko shares up, then down on NZX debut
The company has forecast net profit of $3.7 million in 2014, rising to $9.3 million in 2015. Revenue is projected to be $40.6 million in the current financial year, lifting to $44.7 million in the next.
Gentrack's software is used in 150 utility and airport sites around the world. Energy utilities using its technology include Genesis Energy, Meridian Energy and Vector in New Zealand and Origin Energy and Alinta in Australia.
Its software is used by international airports including Hong Kong, JFK in New York, Newark Liberty, Sydney, Melbourne and Birmingham, as well as Auckland, Christchurch and Wellington.
The company, which was founded in 1989, competes with multinational software giants SAP and Oracle.
Gentrack employs close to 200 staff.
Clifford and chief executive James Docking are the firm's two biggest shareholders, with around 15 per cent and 10 per cent, respectively.