Online grocer Ocado is closing in on its first technology deal with an overseas retailer, disappointing investors who had hoped for news of a firm transaction.

Ocado shares, up around 30 per cent in the last three months, fell as much as 5.5 per cent in early trading.

"While Ocado remains convinced its first global deal will be signed in 2015, the shortage of anything to communicate today is set to reverse some of the company's recent effervescence in terms of share price," said Bryan Roberts of Kantar Retail.

Ocado signed its first third-party deal with British grocer Morrisons in 2013. That helped the firm to report in February a pre-tax profit for the 2013-14 year, the first in its 15-year history. It also said at the time it aimed this year to sign its first technology deal overseas.

"We've progressed conversations quite substantially," chief executive Tim Steiner said.

"We're in discussions with multiple parties and continue to receive inbound interest and some of those discussions are at a very detailed level," he said, adding Ocado's focus remained on north America and western Europe.

Ocado, founded by three former Goldman Sachs bankers in 2000, has divided analysts like few other stocks, with some viewing its home deliveries from giant distribution centres as the future of grocery shopping and others seeing it as a costly and complicated venture that will never make sustained profits.

The firm, whose range includes products supplied by upmarket grocer Waitrose, reported an 11.4 per cent rise in first-half core earnings and a slight acceleration in sales growth despite intense price competition with traditional grocers and deflationary pressures.

For the 24 weeks to May 17, it made earnings before interest, tax, depreciation and amortisation (EBITDA) of £38.2 million, ahead of analysts' average forecast of about £36m and up from £34.3m in the same period last year.

Gross retail sales rose 15.7 per cent to £511.9m, having been up 15.2 per cent in its first quarter.

Though the Waitrose contract runs to 2020, there is a possible break point in spring 2017 requiring 18 months notice. That means in theory either party could serve notice towards the end of 2015.