Genesis Energy's sharemarket debut resulted in $24 million worth of shares being traded in its first three minutes.
Genesis climbed 17% to $1.81 from its listing price of $1.55, giving holders of the 49% that was sold an immediate gain of about $135 million.
The price was underpinned by the massive scaling back of share allocations, which created hot demand, and its attractive potentially high yields.
Genesis' debut at 1pm on Thursday bought to an end the Government's much hyped and controversial partial floating of state owned enterprises, including Mighty River Power and Meridian Energy.
The floats in total raised $4.7 billion for the Future Investment Fund, including $733 million from the Genesis partial float.
More than $143 million worth of shares traded hands in the IPO process, which attracted 68,000 retail investors, giving Genesis the third largest share register on the NZX.
Before the debut, Craigs Investment Partners and Forsyth Barr had the stock valued at $1.92 and $1.65, respectively.
Craigs Investment Partners broker Peter McIntyre said the high share price was prompted by the ''massive'' scaling back of the offer, and the potential ''hyper yields'' from Genesis shares.
''It has been difficult for investors to find pockets [investments] of value in the New Zealand market,'' Mr McIntyre said.
Forsyth Barr broker Andrew Rooney said aside from brokers' scaling back by 20% for the public pool, investors wanting $2500 of shares got 100%.
But thereafter, the scaling became incrementally greater. Applications for $10,000 received just $3467 worth and those wanting $40,000 were scaled back to $5000.
Before the 1pm opening, investors were lodging bids to top up to what they wanted, and sellers were similarly in the market. Some institutional investors were lodging requests for $1 million ''blocks'', he said.
Mr McIntyre noted that while there was an oversupply of electricity in the market at present, and companies were either postponing or cancelling new infrastructure projects, there would, in the medium to long term, ''eventually be a more demand than supply'', Mr McIntyre said.
''I would be very surprised to see a pull-back in price as the yields will hold it up,'' Mr McIntyre said.
