Two journalists who wrote the City Slickers financial column in the Daily Mirror aimed to "manipulate" the stock market, a court has heard.
The reporters failed to state their conflict of interest, the court heard
James Hipwell and Anil Bhoyrul would buy stocks, tip them in the column and then sell at a profit as the price rose, counsel claimed.
James Hipwell has denied charges of breaching the Financial Services Act; Anil Bhoyrul is not on trial.
Another defendant, Terry Shepherd, denies a charge of breaching the Act.
The alleged "share-ramping" took place between 1 August 1999 and 29 February 2000 and involved 44 separate incidents.
Conflict of interest
As the journalists owned shares, prosecuting barrister Philip Katz said there was "an obvious conflict of interest".
"We say any tip which deliberately failed to disclose to readers this conflict of interest created a hugely misleading impression as to the value of shares they tipped.
"The intentional failure by them to disclose what they were really doing is, as far as the two journalists are concerned, the most serious aspect of the case."
Some stories behind the tips "were in fact untrue, inaccurate or otherwise factually misleading," he said.
One example was about the alleged development of an Aids vaccine by Oxford Glyco Sciences, a company featured as the column's "tip of the day". Evidence would show "there was no truth whatsoever" in the claim, Mr Katz said.
He described how Mr Shepherd "helped the two journalists in the misuse of the column to manipulate the market".
His motive, said Mr Katz, was to "bet on some winners" and "make a quick profit".
Mr Shepherd allegedly gained a profit of £17,000, Mr Hipwell £41,000 and Mr Bhoyrul £15,000, although they did not make a profit on every occasion when a share was tipped in the column.
Mr Shepherd, "like the others...believed that the appearance of a share in that column might well have an effect on the price of a share," Mr Katz said.
However, he "stepped over the line into criminality with the others when he started to encourage them to tip shares and persistently helped them by spreading and disseminating that information".
The reporters were sacked by the Mirror in February 2000 after the paper's then editor Piers Morgan bought shares in a company which they had tipped.
Mr Morgan was subsequently cleared of any wrongdoing by a Department of Trade inquiry.