Neil Collins, a columnist for Reuters Breakingviews, broke the news providerâs code of conduct by failing to reveal his stakes in certain companies including Marks & Spencers and BP, the Guardian reported.
A number of other investigations into the conduct of journalists are now ongoing in the wake of his resignation.
In an internal memo to staff quoted by the newspaper David Schlesinger, editor-in-chief of Reuters, said, that the journalist had conducted âmultiple breachesâ of the code.
âWhile we have no evidence the journalist was abusing his position for financial gain, we take such breaches extremely seriously and that journalist resigned with immediate effect during our investigation,â he explained in the message.
More than 50 articles by Mr Collins have been identified by Reuters as potentially being influenced by his business interests.
Disclaimers have now been added to these stories to ensure readers are aware of any potential conflict of interests.
Under Thomson Reuters code of best practice, columnists are not allowed to write news on companies they own shares in unless management are notified.
Content or links to content published as part of Breakingviews are thought to have been included in material printed by the Times and the New York Times.
By Jim Ottewill