Low-ball share buyer Bernard Whimp has made close to $300,000 through an offer made to Vector shareholders by his limited partnership Energy Securities.

The energy company yesterday said more than 300 of its investors had accepted an offer to sell their shares at a price that was significantly less than their market value.

Companies associated with Whimp, a former Christchurch property developer who is now registered to a Sydney address, sent letters to shareholders in seven large listed companies between Christmas and New Year.

Vector, Telecom, Fletcher Building and TrustPower investors were among those targeted with offers to purchase shares at a discount of up to 43 per cent on the market price.

Yesterday Vector said 373,209 shares, or 0.15 per cent of their shares that are available for trading, had been sold to Whimp's company.

Energy Securities had offered $1.56 per share - 34 per cent less than the $2.36 they were trading at on the market on December 29. The difference in the offer price and the listed price could have netted Energy Securities $298,567.

Vector chairman Michael Stiassny said he was concerned shareholders had unwittingly sold their shares at a rate below market value.

"These shareholders did not receive a fair price for their shares and that absolutely galls me," he said.

Stiassny said that while it was up to individuals to make their own investment decisions the board was concerned at the style in which the share offer was made.

He understood the Securities Commission was considering what action it needs to take to ensure investors have confidence in the New Zealand capital markets.

The Securities Commission has previously said unsolicited offers to buy shares below market value are not illegal, but it is against the law to mislead or deceive investors into accepting an offer.

Whimp, who has previously used limited partnerships to get around a four-year ban on holding directorships that ended in October, is able to get hold of shareholders' details through a public register.

Investor advocate Brian Gaynor has said that it is difficult to interpret the term misleading or deceptive and in Australia all offers must be in a written statement setting out the market value of the shares on the day the offer is made.

Gaynor said that disclosure of the sharemarket price and a minimum acceptance period of one month should be mandatory in New Zealand to help improve investor confidence in markets.

It's not the first time Whimp has made money from his offers.

In August, he made offers for four million DNZ Property Fund shares, and bought 2.2 million at 60c each.

Shares in DNZ have since traded at between 99c and $1.25, so Whimp would have made at least $858,000.

He has also been linked to below-par offers to investors in South Canterbury Finance and Strategic Finance.

- Additional reporting NZPA