Inmarsat has rejected a second takeover approach from US rival EchoStar, which valued the UK satellite company at £2.45bn.
Shares in Inmarsat sank 10% to 475p in early trading after EchoStar said its latest cash and share offer of 532p had been rebuffed.
Inmarsat rejected EchoStar’s first approach in June, and reiterated the offer “very significantly” undervalued the satellite operator.
Its initial interest sparked the prospect of a bidding war as France’s Eutelsat Communications said it was considering an offer. However, it quickly dropped out of the race to buy Inmarsat.
EchoStar said it “believes a combination of EchoStar and Inmarsat is strategically compelling”.
It added: “The combined group would be one of the world’s leading satellite providers and be well supported by a global portfolio of complementary assets and service offerings.
“EchoStar believes that the improved proposal presents a compelling opportunity for Inmarsat’s shareholders to realise certain value from their investment in Inmarsat while also participating meaningfully in the upside potential of the combined company.”
The company, which is controlled by billionaire Charlie Ergen, is now seeking an extension of a deadline that requires it to table a firm proposal by 5pm on Friday 6 July.
The British government would be likely to scrutinise any deal because Inmarsat is considered a strategic asset.