UK stocks put in a mixed showing as investor return to their desks after the holidays, with the FTSE 100 index losing earlier gains to nudge lower, although mid caps are putting in a better performance with oil and retails stocks moving. Wall St closed mixed on Friday, while Asian markets were up this morning.

The benchmark FTSE 100 index fails to hang on to early trading gains to reverse 0.5% to 6,513, with oil stocks under pressure as the price of WTI and Brent crude ebbs more than 1% down. BP (BP.) heads the Footsie loser board, shedding more than 3% to 397.9p, followed by Royal Dutch Shell (RDSA) off 1.7% at £21.97 and Tullow Oil (TLW) 1.8% down at 406.6p.

The retail sector comes under pressure as high street bellwether Marks & Spencer (MKS) is marked down 1.6% to 469.4p as SocGen downgrades its rating from 'buy' to 'hold' ahead of Thursday's third quarter update. This could disappoint given reported delivery problems for the retailer in the run-up to Christmas. Tesco (TSCO) and Sainsbury (SBRY) are also off the pace.

Kurdistan oil producer Gulf Keystone Petroleum (GKP) drops 4.2% to 64.2p despite announcing it hit its 2014 40,000 barrels of oil equivalent per day production target. The shares are likely a victim of further weakness in crude prices - which is dogging the rest of the oil and gas sector today - and disappointment the news is not accompanied by another export payment from the Kurdistan Regional Government which controls the semi-autonomous part of northern Iraq.

But more positive are the shares of inkjet printhead technology designer Xaar (XAR), which rally 4.6% to 405p as a new CEO is unveiled to replace the long-standing and respected Ian Dinwoodie, who plans to retire this year. Doug Edwards has been appointed as the new boss, joining immediately from Kodak in the US. 'It is a privilege to be asked to lead Xaar through this next phase of the company's development,' Edwards says today, adding that 'future opportunities in digital printing are substantial.'

Low-cost Irish carrier Ryanair (RYA) adds 2.7% to €10.06 on the back of 20% passenger growth in December. Load factor meanwhile added 7% to 88%.

Cruise operator Carnival (CCL) rises 2.9% to £30.16 after analysts at Berenberg increase their price target from £30 to £35, citing the company's determination to improve return on capital and an optimistic sector outlook.

High purity stevia producer PureCircle (PURE:AIM) sweetens 10p to 530p on a positive first half trading statement. The company, whose products are used in soft drinks including Coca-Cola Life, flags sales up 24% to $43 million in the seasonally weaker half as well as margin improvements.

Small cap Engineer Hayward Tyler (HAYT:AIM) jumps 9.2p, or 13.5%, to 88p after a weekend share tip in the Daily Mail’s MIDAS column.

Shares in Rangers International Football Club (RFC:AIM) jump 15% to 26p as the north of the border footie club confirms that it has received an approach from Robert Sarver  that may or may not lead to an offer being made.

Collagen Solutions (COS:AIM) has agreed a contract with Globus Medical to supply fibrous collagen powder for use in the manufacture of their bone grafting products. That powers the shares 13% higher to 14.125p.

Hydrogen fuel cell technology developer ITM Power (ITM:AIM) has begun a significant expansion of the manufacturing facilities at its Atlas Way site in Sheffield. The expansion includes two new test bays for acceptance testing of HGas Power-to-Gas units and the provision of a new 1MW substation. Its shares rise 1.6% to 32p.

Shares in fabric importer Leeds Group (LDSG:AIM) put on 1.5p to 42p, up 3.7%, as earnings per share for the six months to end-November grow 8.7% to 2.5p. The order book is also stronger year-on-year.

Testing kit-maker EKF Diagnostics (EKF:AIM) rises 2.3% to 21.5p as it shaves £3.3 million off the deferred costs of its DiaSpect Medical acquisition following disappointing sales for the German company in 2014.

Issue Date: 05 Jan 2015