The Nasdaq Stock Market renounced the option of raising its hostile offer for the London Stock Exchange on Friday, leaving its fate with shareholders.
Nasdaq owns almost 30% of the LSE and is offering £12.43 pence a share in cash for the rest, valuing the operator at £2.7 billion ($5.3 billion).
Under UK takeover rules, the bid has until February 10 either to lapse or go unconditional. The number of LSE shareholders who have voted has not been announced.
Any increased offer by Nasdaq for LSE would have to have be agreed by both companies.
The two exchanges have engaged in a war of words in recent weeks, with Nasdaq criticising the London exchange for refusing to discuss the prospect of an agreed take-over deal.
Earlier this week, LSE rejected the criticism, saying Nasdaq had not sought "constructive discussion with the exchange".
The pace of mergers is picking up among the world's stock exchanges as they come under pressure from customers to offer global services and cut fees. Competition is also becoming more intense, with a group of investment banks planning to create a pan-European equity trading platform this year.
The LSE has long been a takeover target, in part because of its relatively small market capitalisation compared with rivals. Its shares have more than trebled over the past two years as it has received and rejected a string of offers.
Nasdaq CEO Bob Greifeld is optimistic the bid will succeed. Speaking yesterday on the sidelines of the World Economic Forum of business and political leaders in Davos, he said he was optimistic for the level of acceptances next week.
