Shares in construction company Vinci fell more than 18 per cent after the circulation of a fake press release said the firm would restate its accounts and sack its chief finance officer, Christian Labeyrie.
In a real release on its website titled "Vinci's denial" it said:
A fake press release was published today by Bloomberg at 4.05pm. Vinci denies formally all the information in this fake press release and is investigating all legal actions in furtherance thereof.
Once the denial was issued, it was business as normal for the firm's share price, as it recovered to end the day down just under four per cent at €58.8.
A press release that appeared to come from Vinci appeared just after 4pm Paris time, claiming it would restate its financial statements for 2015 and the first half of 2016 as a result of an internal audit, uncovering a net loss for the two periods.
Vinci sounded the alarm 24 minutes later, saying it was a victim of a hoax and the release had been sent from a fictional member of the group's communications team in order to undermine its business.
France's AMF financial regulator said it would look at the situation and might stage a full investigation.
Facebook and Google responded to criticism over the vast amount of fake news during the US Presidential race, by saying they would crack down on advertising against the content.
The Washington Post had found the top result when searching "final election result" on Google was a link to a fake news site claiming that Donald Trump won both the electoral vote and the popular vote, when he didn't.