London pre-open: G7 warns of Brexit risks

The fact that investors are heading into a long weekend on both sides of the Pond, ahead of key risk events next week including the US jobs report for May and an OPEC summit is also expected to restrain activity today.

With little doubt, all eyes are on Yellen´s speech at Harvard University, which is scheduled for 15:30BST; although the possibility exists that she will not make policy relevant remarks, even the risk that she might is enough to keep many traders on the sidelines.

The Footsie is seen starting the day 3 points higher from Thursday closing mark of 6,265.65.

"At the moment, it is all about Miss Yellen and all focus will be on her as she takes to the stage later today. Many think that she will be very hawkish and possibly reverberate the same message as her fellow colleagues; that the US economy warrants another rate hike," said Naeem Aslam, chief market analyst at Think Forex UK.

“We don’t think it’s the right venue,” said Michael Gapen, chief US economist at Barclays Investment Bank. “I would be surprised if she made comments.”

Any comments would come after a hawkish set of FOMC minutes last week and several Fed governors adding since then that two to three rate hikes were on the table in 2016, possibly including at the next meeting, on 14-15 June.

Acting as a backdrop, following their meeting at Ise-Shima, in central Japan, G7 leaders warned of the damage that Brexit might inflict.

“A UK exit from the EU would reverse the trend towards greater global trade and investment, and the jobs they create, and is a further serious risk to growth,” they said in an official statement.

The main Asian stock gauges are broadly higher, with the Shanghai Stock Exchange´s Composite Index standing 0.22% higher at 2,828.57 as of 07:30 BST.

To take note of, reports indicate that Japanese prime minister Shinzo Abe might announce a decision to postpone a planned increase in the country´s consumption tax in April 2017.

Linked to the above, figures released overnight revealed that core consumer prices in the Tokyo area - a lead indicator for price pressures in the world´s third-largest economy - slipped to a -0.5% year-on-year clip in May (consensus: -0.4%).

On the data front, the main releases on Friday will be a second reading on US first quarter GDP at 13:30 BST followed ninety minutes later by the University of Michigan´s consumer confidence survey results for the end of May.

Finance post up for grabs at Wolseley

Wolseley said on Friday that Simon Nicholls will not take up his role as chief financial officer later this year, as announced back in January, without giving any reasons. The FTSE 100 building materials group said David Keltner, current CFO of US subsidiary Ferguson Enterprises, will be appointed interim group CFO on 1 September and the selection process to appoint a permanent CFO will commence immediately. The company confirmed Ian Meakins will retire on 31 August 2016, while John Martin will succeed him as CEO on the 1 September as expected.

Phamaceuticals giant AstraZeneca announced positive results for its Faslodex drug for the treatment of metastatic breast cancer in post-menopausal women who have not had prior hormonal treatment for home-receptor-positive breast cancer. The company said on Friday that Faslodex met its primary endpoint of extended progression-free survival.

In addition, AZN said the US Food & Drug Administration has issued a complete response letter on the new drug application made for sodium zirconium cyclosilicate, the investigational medicine being developed for the treatment of hyperkalaemia (high potassium level in the blood serum) by wholly-owned subsidiary ZS Pharma.