Weakness in energy stocks, pulled lower by downbeat results from Royal Dutch Shell (RDSa.L), offset gains from banks and miners leaving Britain's FTSE 100 .FTSE off 0.3 percent by midsession on Thursday.

Investors were cautious ahead of U.S. GDP data, which will be closely eyed for clues on the timing and pace of a recovery in the global economy.

At 1139 GMT, the FTSE 100 .FTSE index was 13.26 points lower at 5,067.16, having closed down 120.55 points, or 2.3 percent, at 5,080.42 on Wednesday, its biggest one-day percentage fall since July 2.

There's been a bit of a pullback as there's been a pause in positive corporate and economic newsflow, said Graham Secker, UK equity strategist at Morgan Stanley.

But that's not necessarily a bad thing, as it means that authorities won't be too hasty in retreating from their stimulus policies.

Oil giant Royal Dutch Shell (RDSa.L) was the biggest blue chip faller, down 4.4 percent after it said third-quarter net profits fell 73 percent, hit by falling oil and gas prices and refining margins, and Chief Executive Peter Voser warned of a slow recovery.

Shell's numbers ended a mixed batch of third-quarter results for the energy majors, with BP (BP.L) beating forecasts on Tuesday but BG Group (BG.L) missing output forecasts on Wednesday.

BG Group shares shed 2.2 percent, while BP fell 0.2 percent, and oil explorer Cairn Energy (CNE.L) lost 0.6 percent with its latest interim management statement failing to excite.

U.S. third-quarter GDP numbers, due at 1230 GMT, will give investors a further idea as to the durability of the perceived recovery after a shock fall in UK Q3 GDP on Friday.

According to a Reuters poll of 77 economists, the U.S. economy is expected to have grown 3.3 percent at an annualised rate in the third quarter, after shrinking 0.7 percent in the second.

BANKS BOUNCE BACK

Banks were the biggest blue chip gainers, bouncing back after sharp falls earlier this week on concerns over possible break-up calls from the European Commission following a move by Dutch peer ING (ING.AS) to split in two.

Lloyds Banking Group (LLOY.L) gained 8.6 percent as it confirmed it is considering raising capital via a rights issue and debt swap as an alternative to a costly government scheme to insure it against credit losses. 

The bank, 43 percent state-owned after receiving a 17 billion pound ($27.95 billion) bailout last year, said it was in advanced discussions with the British government and regulators over its potential capital raising.

Part-nationalised peer Royal Bank of Scotland (RBS.L), also thought to be looking at plans to reduce its exposure to the government's asset protection scheme, was the top FTSE 100 riser, up 11 percent, while Barclays (BARC.L) gained 3.3 percent and HSBC (HSBA.L) added 0.5 percent.

Asia-focused bank Standard Chartered (STAN.L) added 0.8 percent after it said it said it was benefiting from growth across its franchises but cautioned the economic outlook remains fragile. 

Miners were also stronger as metal prices held steady. Rio Tinto (RIO.L), Xstrata (XTA.L), Lonmin (LMI.L) and Anglo American (AAL.L) added 0.3-3.3 percent.

Drugmaker AstraZeneca (AZN.L) gained 0.8 percent after it reported Q3 earnings per share and sales well above market expectations. 

Other pharmaceuticals were weaker, however. GlaxoSmithKline (GSK.L) which reported slightly disappointing figures on Wednesday shed 1.1 percent, and Shire (SHP.L), which reports on Friday, fell 0.1 percent.

Among the mid caps, National Express (NEX.L) was the biggest faller, down 9.6 percent, after bus and rail peer Stagecoach (SGC.L) said National Express has decided not to pursue proposals for a merger. [ID:nLT510199]

Stagecoach shares gained 2.4 percent.

U.S. jobless claims for the week ending Oct. 24 will come under scrutiny later in the session.