The Financial Markets Authority is looking at other offers made by 'low-ball' share trader Bernard Whimp.
The Wellington High Court on Thursday ordered that Mr Whimp cancel offers made to investors in six listed companies.
The authority's chief executive, Sean Hughes, says it is focusing on transactions where Mr Whimp offered less than the market price.
Mr Hughes says new powers have enabled the authority to investigate Mr Whimp's offers more closely.
Mr Hughes says Mr Whimp's actions make people think the market is a dangerous place and are a scourge on what is otherwise a transparent and well-functioning market.
Nearly 1200 investors holding $7.2 million worth of shares in six listed firms accepted deferred payment offers from Mr Whimp.
While the offers appeared to be at a significant premium to the market price, the fine print revealed that the investors would be paid in instalments over 10 years, thereby undervaluing the shares.
Apart from a small number of investors who confirmed they want to sell, the High Court cancelled the remaining agreements made to sell shares to Mr Whimp.
Of the 149 who have accepted, Mr Hughes says the FMA has the authority to check if 132 are genuine.
Meanwhile, the High Court issued a permanent injunction against Mr Whimp from engaging in similar behaviour.
The decision does not affect Mr Whimp's previous 'low ball' offers.
Mr Hughes told Morning Report that Mr Whimp has been ordered to display a prominent warning from the Financial Markets Authority on these offers telling investors that the offers are not in their best interests.
Read the fine print - investor
An elderly investor says what happened to him is a warning to others to read the fine print.
Les Goatham, who is retired and lives in Dunedin, agreed to sell about $6700 worth of shares.
Mr Goatham says he did not read all of the contract and missed the clause on the back page which said the payment would be made over 10 years.
He has written a letter cancelling the agreement, but says he has heard nothing.
