By Alistair Smout
LONDON (Reuters) - Britain's top share index edged lower on Friday, set to finish the week with falls as recent weakness in the pharmaceuticals continued, with investors wary over political risk in the sector.
By 0900 GMT, the FTSE 100 (FTSE) was down 4.20 points, or 0.1 percent, at 6,812.70, down 0.7 percent for the week and set for a second straight weekly fall.
Investors were awaiting a speech by Federal Reserve Chair Janet Yellen at a summit in Jackson Hole, due at 1400 GMT, before making strong bets on the market, traders said.
The pharmaceutical sector was the biggest drag on the index for a second straight day, trimming 6.7 points off the index.
It has been under pressure since U.S. Presidential candidate Hillary Clinton criticised the pricing of a high-profile drug.
Shire (L:SHP) fell 1.2 percent, but remains up 41.5 percent since lows in February. After a strong run, analysts said that the sector was now vulnerable.
"Investors are pulling funds from what now seems to be one of the most politically-sensitive industries in the run up to the US presidential election," said Jasper Lawler, market analyst at CMC Markets, in a note.
CRH (L:CRH) fell 0.9 percent, after posting a 2.9 percent rise following results on Thursday.
The building materials firm raised its dividend for the first time in 7 years, and many brokers lifted their target prices on the stock.
However, Societe Generale (PA:SOGN) cut its rating on the stock to "hold" from "buy".
"CRH reported a good set of numbers yesterday... But we believe the current stock price already factors in the medium term growth potential," analysts at SocGen said in a note.
BAE Systems (LON:BAES) rose 2.1 percent, benefiting from an upgrade by Berenberg.
Glencore (L:GLEN) bounced back from falls after results earlier this week. It was up 2.6 percent, the top FTSE 100 riser, but remained down for the week as a whole.
Copper prices also stabilised after falls this week, while the price of zinc hit a 15-month high. In all, miners (FTNMX1770) rose 1.5 percent.
The FTSE was unaffected by data showing that GDP was in-line with preliminary readings, and growth held up well ahead of Britain's decision to leave the European Union.
Among mid-caps, the Restaurant Group (L:RTN) rose 7 percent after beating expectations with results, while Amec Foster Wheeler rose 5.9 percent after an upgrade to "overweight" by Morgan Stanley (NYSE:MS).