CNBC reported that Salesforce and Google may make a formal bid shortly, causing shares to jump 20.6 per cent to $22.38 in late morning trading in New York.
Reuters later quoted a source, saving the company has initiated talks with "several technology companies"
Why Twitter, why now?
Twitter has been regarded as an increasingly attractive takeover target in recent months: its share price has fallen as it struggled to engage users. While figures in July showed revenues had come in at $602m in its second quarter, up 20 per cent on the year before, it missed analyst expectations of $606m.
Meanwhile, it lowered third-quarter guidance to between $590m and $610m - down from the $678m analysts had expected.
Turning around the supertanker
At the beginning of this month, shares tumbled after reports suggested chief executive Jack Dorsey - who is also the chief executive of NYSE-listed Square - was under pressure from its board to cut costs.
It's frequently the subject of takeover rumours - in August, it was reported former Microsoft boss Steve Ballmer and Saudi investor Prince Al-Waleed Bin-Talal were considering making an offer. Although shares jumped then, investors weren't as enthusiastic as they are today: shares rose a comparatively modest eight per cent.
Salesforce said it doesn't comment on rumour or speculation.
Neither Google nor Twitter had responded to requests for comment at the time of publication.