Online grocery giant Ocado’s shares have been driven higher than ever by a mixture of takeover and stake-building speculation.

Ocado’s share price has doubled to around 239p in recent weeks. Yesterday it was at 239p, a record high, ahead of its full year results due out in a week.

Speculation is rife that one of its big rivals is mooting a takeover. Some believe Morrisons is having a look, as the grocer currently does not have an online operation, while others believe it could be Asda, and some even Tesco.

Others have speculated about Waitrose, which Ocado has a supply partnership with.

Others believe a US investor has been increasing its stake, driving up the value.

Nick Bubb, analyst at Arden Partners, said Morrisons boss Dalton Philips has promised to come up with a different business model for home delivery so it “makes no sense” to bid for Ocado. He added: “In some ways it would make more sense for Waitrose itself to buy Ocado, but that is hard to reconcile with the sell-down of the John Lewis shareholding over time.”

He said the “real answer is that an American stakebuilder is at work, although whether that is an institutional fund or a giant online company with tons of cash remains to be seen”.