Subsea 7 share soared amid rumours of a merger with US service giant Baker Hughes.
Reuters news agency cites a Wall Street Journal report, which quoted anonymous sources.
It was claimed that talks broke down over a price for the reported takeover.
Subsea 7 said it was aware of the media speculation and share price movement but had a policy of not commenting on “rumours”.
The share price spiked on Thursday morning around 10am at $17.43.
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