The insider trading is suspected of having taken place on 18th and 19th September.
“These were large volumes and big price movement. Plus that we now now that news was made public,” said prosecutor Robert Engstedt of the Swedish Economic Crimes Bureau.
OMX shares rose sharply on September 18th, a Tuesday. The following day they fell by 7 percent, after which trading in OMX was suspended. On the morning of 20th September Nasdaq and Borse Dubai made their deal public. Several media had already published information about the agreement.
Suspicions were raised at both Finansinspektionen (FI), Sweden’s financial services regulatory authority, and the Stockholm Stock Exchange. They reported the matter to the Swedish Economic Crimes Bureau.
Engstedt was on Tuesday giving few details about his investigation. He would not say whether he knew who lay behind the share purchases, whether anyone had formally been declared a suspect or how the investigation would proceed.