Broker tips: M&S, AB Foods, Rolls-Royce, Centamin

Marks & Spencer's shares surged on Wednesday after the retailer impressed with a surprise increase in first-half profits, and while the market welcomed the bottom-line beat analysts raised concerns with a continued underperformance in clothing sales.Analysts at Numis Securities maintained a 'hold' recommendation, saying that full-year consensus forecasts are unlikely to change in spite of the first-half beat. "We expect the challenging trading conditions and M&S' ongoing LFL underperformance in GM will result in full-year PBT forecasts settling around £650m, slightly light of the current consensus (£655m)."Citigroup has trimmed its profit forecasts for Associated British Foods due to an ongoing weak sugar performance, but has lifted its stance on the stock from 'neutral' to 'buy' on prospects for its fast-growing retail chain Primark."Primark's international expansion programme remains very successful, a theme we expect to continue for many years to come."Panmure Gordon has downgraded Rolls-Royce from 'hold' to 'sell' after the engine maker announced plans on Tuesday to accelerate its cost-cutting programme with 2,600 job cuts over the next 18 months."For us, this was just another profit warning, issued only a few days after the previous warning," said Panmure analyst Sanjay Jha. "More importantly, it suggests that far from being 'well positioned in growth markets' the management is now dealing with a group in decline, despite record order books, and is struggling to stay on top of events," he said.Centamin's downgrade to production guidance on Wednesday was disappointing but not wholly unexpected, according to analysts at Peel Hunt and Westhouse Securities who kept 'buy' ratings on the stock.