United States data centre owner Digital Realty Trust and Australian industrial property owner Goodman Group have acquired a near 10 per cent stake in troubled Australian data centre operator NextDC for about US$476 million.

Digital Realty and Goodman said on Monday that a jointly owned special purpose vehicle had paid A$9.22, or US$6.33, a share for a 9.9 per cent interest in the ASX-listed data centre operator. The partners said they had no agreement to engage further and neither planned to make a takeover offer, but both reserved the right to do so in future.

"Digital Realty and Goodman Group are each highly experienced investors in the data-centre sector and look forward to a potential collaboration with the NextDC board and management on the ways and forms in which the parties may help to address the challenges facing the company," the pair said in a statement.

The purchase completes a share raid launched last week. On Wednesday, 4 November, Goodman and Digital Realty offered to buy up to 9.9 per cent of NextDC in a deal worth about A$715 million, or US$501.14 million, through an aftermarket bookbuild run by an entity the two companies own equally. The bookbuild was priced at A$9.50 a share, a 45.5 per cent premium to NextDC's closing price the day before.

NextDC shares rallied sharply on the news, jumping as much as 45.8 per cent to A$9.52 in early trade on Thursday, 5 November, and eyeing their strongest intraday gain on record. The stock had lost 45.8 per cent in October.

NextDC's board called the move opportunistic. It said it had received no takeover proposal and noted that the raid came two weeks after the company announced a power delay at its M3 Melbourne site, cut its earnings guidance and shelved new development. The board said it would consider any bona fide takeover approaches on their merits and told shareholders they need not take any action.

Last month, NextDC's stock tumbled 42 per cent to a nearly nine-year low of A$5.35 after delays to construction at one of its Melbourne facilities prompted it to slash its earnings guidance, raising worries among analysts about how it would fund other developments. In October the company also said it would shelve all new development projects and land acquisitions for the foreseeable future, and evaluate capital recycling opportunities, including potential sales of selected development sites.

The completed purchase price of A$9.22 a share is below the A$9.50 a share offered in Wednesday's bookbuild, but still far above the level NextDC traded at before the raid. The stake gives two rival data centre operators a seat at the table of a company whose shares have been under severe pressure, without either of them committing to a full bid.

Whether the stake leads to a takeover approach remains open. The buyers have said they have no intention of submitting a control proposal or making a takeover bid for the company at this time, but have reserved the right to do so. Under Australia's takeover rules, the price they paid also sets a floor: any takeover bid by Goodman, Digital Realty or their associates in the coming months must be at least A$9.50 a share, the price offered in the bookbuild.