The US company Kraft, whose brands include Heinz ketchup, Capri-Sun and Kool-Aid, is still hoping to close a deal according to the BBC.
Unilever is currently valued at more than £100b and today its share prices has surged by 12% in London to £37.66.
Neil Shan, director of research at Edison Investment Research, said the deal is a reflection of the surge in dollar buying power and the decline in Sterling.
He said: "Today's 10% rise in Unilever's share price means this is cash neutral for a US purchaser compared with if it had approached seven months ago. Unilever's own share price is also down about 15% from its all time highs since the UK referendum vote last summer, on concerns about its pace of global sales growth, so the timing of Kraft Heinz's bid is opportune. Kraft Heinz will look to justify a bid value of Unilever based on its average price over the last three months, which has been over sold and does not reflect the inherent value of long-term cashflows built into Unilever's model. Kraft, which had already been demerged from Mondelez snacks arm, is now looking to create a behemoth in the entire food supply chain from ingredients to products on the shop shelf along with access to all of Unilever's other FMCG world leading consumer brands."
In 2010, Kraft aquired chocolate giant Cadbury for £11.5b, but no longer owns the company following its merger with Mondelez. It bought Heinz in 2015.
Jonathan Buxton, head of consumer and retail at Cavendish Corporate Finance said a marriage between Kraft and Unilever would "bring into one family some of the world's most famous consumer brands and give the merged company an unprecedented scale and reach in the global consumer goods sector".
Buxton said: "Motivation for the deal is less benign, with both businesses suffering growth and sales pressures as brand loyalty is more difficult to engender in increasingly capricious consumers. Growth forecasts for the global packaged goods sector are also restrained prompting greater focus on potential mergers and acquisitions. Unilever's markets, focused on Europe and Asia, are complementary to Kraft Heinz's US-focused business, but whether the two companies' corporate cultures would be an equally good fit is less certain. This is no doubt an opening bid, which has been rejected, and we expect Kraft Heinz to come back with a sweeter offer."
The Unite union said that it was seeking an urgent meeting with Unilever bosses to urge the company to resist takeover attempts by Kraft.
National officer Rhys McCarthy said: "Unite members make household products which are much loved by UK consumers. Kraft Heinz and their backers' reputation for cost cutting, we believe, will lead to great brands being harmed through job cuts and a never ending drive to push costs down.
"This takeover bid, is we fear, driven by a desire for a growth in sales, not through product innovation and maintaining great brands, but by gobbling up a major competitor and slashing costs to generate a quick buck.
"Unite does not believe this takeover is either in Kraft Heinz workers' interests or those of Unilever and that ultimately it will lead to jobs losses and poorer products for consumers."
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