Mumbai: Nasdaq and Borse Dubai raised their offer for OMX to $4.9 billion in a bid to flush out potential rival bidders and came closer to a majority stake in the Nordic exchange group.

Borse Dubai is offering 265 Swedish crowns ($40.57) per share, up 15 per cent from a previous offer of 230 crowns. It has now secured 47.6 per cent of OMX in stock or options for shares.

The two increased their stakes after the Qatar Investment Authority (QIA) started buying OMX shares at 260 crowns last week.

The two exchanges said their offer is binding unless a competing bid is made for at least 303 crowns per share.

The bid values OMX at $4.9 billion, compared with Borse Dubai''s previous offer of $4 billion.

Borse Dubai chief executive Per Larsson said he was in talks with OMX shareholders and hoped to boost the holding in the firm to more than 50 per cent "fairly soon".

Last week Borse Dubai agreed with Nasdaq to go ahead with its OMX bid and then sell the Nordic exchange to the US stock exchange company in return for a 20 per cent stake in the combined group.

Nasdaq and Borse Dubai also changed the minimum acceptance level to above 50 per cent from 90 per cent.

Larsson said the objective was still ultimately to buy 100 per cent of OMX.

Borse Dubai and Nasdaq said they had irrevocable undertakings from major OMX shareholders Investor and Nordea to acquire their stakes. Investor owns 10.7 per cent of OMX and Nordea 5.2 per cent.

The Swedish government, which holds a 6.6 per cent stake in OMX, said it was studying the new offer, which it considered an "interesting proposal".

The Qatar Investment Authority, which last week began acquiring OMX shares, now owns 9.98 per cent. QIA also bought a 20 per cent stake in the London Stock Exchange last week.

Trading in OMX shares resumed today after it being suspended was up 2.8 per cent of the new bid level at 273 crowns by 1210 GMT amidst a spate of offers.