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* FTSE 100 down 1.2 pct
* Micro Focus plummets after CEO quits, revenue outlook cut
* Barclays rises after activist acquires voting rights
* Hammerson jumps after Klepierre approach
LONDON, March 19 (Reuters) - A plunge in Micro Focus' share price on a gloomy revenue outlook sent the UK's top share index down to a two-week low on Monday, with weakness in commodities-related sectors adding pressure.
Barclays jumped around 4 percent after activist investor Sherborne acquired 5 percent of voting rights in the bank.
Investors have been putting pressure on Barclays to become a profitable investment banking force. It has struggled due to low volatility and tougher regulations on capital requirements.
The blue-chip FTSE 100 index was down 1.2 percent at 7,077.00 points by 1005 GMT as materials and energy stocks fell on the back of weaker metals and oil prices.
Shares in software company Micro Focus plummeted 58.5 percent and it was on track for its biggest ever one-day loss after its CEO quit and it cut its revenue outlook.
Micro Focus has had problems stemming from assets it bought from Hewlett Packard Enterprise, on which it spent $8.8 billion in 2017.
"Large acquisitions are inherently risky as they come with integration challenges. Micro Focus appears to have underestimated these challenges and is now suffering," Russ Mould, investment director at AJ Bell, said.
Micro Focus fell around 17 percent back in January after a disappointing set of results and outlook.
Elsewhere British mid caps were down just 0.3 percent, outperforming the broader European market, propped up by a 25 percent jump in Hammerson's shares.
Shares in the UK retail landlord rose following news that it had been approached by French shopping centre operator Klepierre earlier in the month.
Hammerson rejected Klepierre's takeover bid, valued at 4.88 billion pounds ($6.80 billion), saying it "very significantly" undervalued the company.
As Brexit uncertainties continue to weigh on UK stocks, overseas businesses have found cheaper UK companies attractive takeover targets.
"It's pretty clear that large UK companies are being staked out by potential overseas interest," Ken Odeluga, market analyst at City Index, said.
"There's a bit of undervaluation creeping in because of potential threats around Brexit, real or imagined, and that can make companies quite attractive, and then many are willing sellers because of the same reason," Odeluga added, pointing to CME's bid for NEX Group last week.
(Reporting by Kit Rees; Editing by Jon Boyle)