Labour leader David Cunliffe has again warned potential investors to think carefully about buying shares in Meridian Energy.
The three-week sale of shares in 49% of the state-owned energy company began at midnight on Sunday.
Mr Cunliffe says people need to take into account Labour's plans to set up a single purchaser of electricity, called NZ Power.
"We've announced Kiwi power, which means we'll be buying power for all New Zealanders and making sure there's no monopoly rents in the system which mean people are paying too much.
"So people can make up their own minds about whether the shares are as gold plated as the government was trying to sell them."
Mr Cunliffe says people are being subsidised to buy shares in Meridian because the Government is giving them a "cushy" time-payment option to buy in two instalments.