Australian regulators are still investigating how a Green protest group targeted a leading coal mining company with a hoax email that hit its share price.
As hoaxes go, this was an elaborate exercise and it sucked in a good many people, Radio New Zealand's Sydney correspondent said.
The company Whitehaven Coal is developing a new mine in an environmentally sensitive area of New South Wales.
A green protest group called Frontline Action on Coal sent out a fake news release from ANZ Bank saying a $A1.2 billion loan to fund the project had been withdrawn.
The news sent Whitehaven's coal price down as much as 9% before the hoax was discovered.
While the share price recovered, the hoax has led to calls by the stock exchange to media outlets to slow the speed at which they turn round news. In this case, newspapers published the story online without making any checks of their own.
Regulators also have in their sights investment banks that seek to manipulate the market during takeover negotiations.
Last year, paint company Dulux issued a takeover bid for listed company Alesco in July, declaring the $210 million bid as final. But then it continued to negotiate for months on a better price.
Now the Australian Securities and Investments Commission has warned companies that if they say an offer is final, it should be final. Otherwise, small shareholders who sell on the initial statement suffer.