The head of Borse Dubai has defended the stock exchange’s move to acquire a stake in the rival OMX, despite the leading Swedish regulator finding it guilty of buying the shares illegally.

“We believe that we acted in good faith and according to the rules and regulations,” Per Larsson, the Borse Dubai chief executive, said yesterday. “But we acknowledge that the Swedish regulator has come out with this decision today.”

The state-backed exchange operator, which has offered to buy OMX for $4 billion (£2 billion), has been at the centre of a dispute over how it secured more than 28 per cent of the Nordic market operator’s stock without making an official announcement to the stock exchange.

In a ruling yesterday, the Swedish Financial Supervisory Authority (FI) found that Borse Dubai broke the law when it bought the large stake on August 9 without simultaneously launching a takeover bid for the company.

Borse Dubai, which is vying for control of OMX with Nasdaq, the American exchange, accumulated a direct 4.9 per cent stake in OMX. However, it also struck a series of option deals with hedge funds that gave it the right to own a further 23.5 per cent of the exchange.

Gent Jansson, the acting director-general of the FI, said that the regulator had decided not to fine Borse Dubai because the exchange launched its $4 billion bid for OMX eight days later.

“Our offer is still valid,” Mr Larsson told The Times yesterday. Mr Larsson, who ran OMX before joining Borse Dubai, was in London for a European roadshow to talk to Nordic regulators, shareholders and other parties about the rationale behind Dubai’s counter-bid for the Stockholm-based OMX.

The offer has dealt a blow to Nasdaq, which previously had agreed to acquire OMX for $3.7 billion and has signed irrevocable agreements with management and key shareholders over the deal. Those have lapsed now that a higher bid is on the table.

The Dubai offer has met with resistance in Stockholm. Officials have branded the bid as hostile and have refused to meet Mr Larsson. The continuing investigation into Dubai’s buying of stock has also cast a shadow over its bid.

Mr Larsson said: “We couldn’t talk to the board so we turned directly to shareholders with our offer that, at this point, is higher than Nasdaq’s.” The aim is to send out the offer document to OMX shareholders on September 6, which will set the official clock ticking.

Borse Dubai hopes to close the deal by the end of the fourth quarter. However, Mr Larsson acknowledged it was likely that Nasdaq, which has been trying to boost its presence in Europe but so far has failed, would come back with a higher bid.

This week Nasdaq announced its intention to sell its 31 per cent stake in the London Stock Exchange in an effort to free cash and focus its efforts on OMX.

Mr Larsson declined to comment on whether Dubai had more firepower than its US rival, saying only that he hoped to win over shareholders with its “very strong logic” for a deal.

He added that the aim of the combination was to bring OMX’s world-class exchange technology to Dubai.

“Our industrial logic is to take OMX to our region because it is the fastest-growing region in the world,” he said. “We want to build OMX as a brand, build on the management and the technology.”

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