LONDON (Reuters) - Micro Focus International MCRO.L will miss its full-year revenue target, prompting an accelerated operations review, sending the British IT group's shares plunging.

FILE PHOTO: Signs outside the offices of British IT company Micro Focus International in Newbury, Britain, September 8, 2016. REUTERS/Eddie Keogh

Shares in the group, which focuses on the unfashionable software that still underpins many businesses, fell as much as 34% to a 16-month low of 10.26 pounds after Thursday’s unscheduled update, which the company blamed on weak sales execution and a deteriorating economic environment.

By 0930 GMT they were trading 23% down at 11.93 pounds.

The company downgraded its revenue forecast for the year to Oct. 31 to between minus 6% and minus 8%, compared with previous guidance of minus 4% to minus 6%.

“We have determined that it is appropriate to accelerate the undertaking of a strategic review of the group’s operations with a view to determining where performance can be improved and how the business can be better positioned to optimize shareholder value,” said Chief Executive Stephen Murdoch.

Micro Focus has grown by acquiring legacy technology such as mainframe computer software used by banks, retailers and airlines, driving shareholder returns with a ruthless focus on its bottom line.

It has struggled, however, to integrate assets bought from Hewlett-Packard (HP)HPE.N for $8.8 billion in 2017. The deal was the largest undertaklen by Micro Focus, which had a market capitalization of $6 billion before the HP transaction.

Integration problems after the deal caused the British company to issue a revenue warning and ditch its CEO in March last year.

The shares more than halved after that warning and it took almost a year to claw back the losses.

Thursday’s update did not specify which parts of the group’s business were underperforming beyond saying that weak sales execution had been compounded by a “deteriorating macro environment resulting in more conservatism and longer decision-making cycles within our customer base”.

It had reiterated its previous guidance as recently as last month, when it reported a 5.3% fall in first-half revenue.

Analysts at Barclays noted that the latest guidance was a revision amounting to only 2 percentage points but said the market would clearly recall the more substantial profit warning in March 2018.

“Unlike last time, there is no commentary on profitability in today’s statement,” they said, adding that, with Micro Focus already working hard to cut costs, the revenue drop would nearly all feed through to core profit.