IAG slides on virus worries Despite spending most of the day in the red, the FTSE 100 managed to rally late in the afternoon to close up 6.78 points at 6,631.76, eking out its eighth consecutive session of gains and helped by better than expected retail sales data from the US. Nevertheless, falls in banking shares, which were among the worst performers, dragged on the benchmark index throughout the day. Worries over Standard Chartered's debt weighed on its equity, after it emerged influential short-seller Carson Block had the Asia-focused lender in his sights. Mr Block revealed on Friday he is betting against the bank's debt by buying credit-default swaps, news that unnerved Standard Chartered investors, who sent the shares sliding 30½p to £15.52½, the biggest fall on the main board. At the same time, Investec analyst Ian Gordon argued that investors should switch into Standard Chartered from HSBC, which he cut to "reduce" from "buy" following a strong run from the shares. HSBC shed 5.2 to 739.6p as a result. Following confirmation of the impending departure of Sir Win Bischoff as chairman of Lloyds Banking Group, shares in the lender slipped 0.85 to 58.09p, while with pressure growing on Co-op Bank, the rest of the FTSE 100 lenders were out of favour. Royal Bank of Scotland lost 2.1 to 297.4p and Barclays ended 1.85 worse off at 312.55p. Elsewhere among the fallers, education group Pearson slid 9p to £11.97 on news New York City was considering ending its contract with the company after a mistake in marking school tests. Another laggard in London was Ocado, which dropped 14.6, or 6.5pc, to 210p amid worries that its potential tie-up with Wm Morrison, up 3 at 291.8p, will damage its existing relationship with Waitrose. Mid-cap bingo company Rank Group was also on the back foot and declined 5 to 161p after disclosing the recent cold weather had hit trading. Rank said like-for-like revenue in the 18 weeks ending May 5 fell 2pc. But platinum miner Lonmin pleased with its latest market update and advanced 7.2 to 286p. The FTSE 250 group - at the epicentre of the industrial unrest that swept through South Africa's mining industry last year - lifted its guidance for full-year production and revealed that pre-tax profit during the first six months of the year climbed to $54m (£35m) from $18m in the same period in 2012. Petropavlovsk, the gold miner hit by market worries of possible covenant breach during last month's yellow metal sell-off, added 3 to 149.1p after unveiling plans to save $160m, in an effort to cut debt and bolster cash flow. Recording the biggest gain on the mid-cap index, however, was temporary office space supplier Regus with a rise of 7½ to 177½p - an all-time high and boosted by an upgrade to "neutral" from "underweight" by analysts at HSBC, who were impressed by the group's cost performance in the second half of 2012. Analyst musings were also behind the 21 increase to 942½p in Capita shares on the FTSE 100. Espirito Santo experts raised their recommendation on the company to "neutral" from "sell," arguing the outsourcer should deliver pleasing revenue growth in the medium-term, either through acquisitions or organic expansion. Lower down the scale, there was once again considerable retail interest in Aim-listed outsourcing group Quindell Portfolio, although this time punters were sending the shares sharply higher after they dived almost 55pc last week. Quindell has been under pressure ever since it disclosed a derivative contract, linked to its share price, in its full-year results last Tuesday and a clarification statement issued just before the close on Thursday failed to halt the slide in its shares. Today, two statements from Quindell boosted the group. The company said it would hold a series of "teach-ins" for institutional investors and analysts aimed at assuaging concerns over its business model. Regarding the controversial equity swap derivative, Quindell stressed that "there are no circumstances under which the company would have to issue more shares pursuant to the equity swap or have to pay out any further cash regardless of the performance of the equity swap." Quindell shares gained 1.1, or 18.3pc, to 7.1p, although they remain below the 13¼p they opened at last week.