The share price of High Street giant Marks & Spencer (M&S) received a boost on Thursday after Exane BNP Paribas upgraded the stock by two notches from 'underperform' to 'outperform', expressing confidence in the retailer's turnaround. With the stock's valuation near 10-year lows, the broker said that "now is the time to look beyond recent troubles" as it lifted its target price by 46% from 390p to 570p.Analysts said that the group has experienced three years of difficult trading and pro?t declines with margins having fallen to their lowest in a decade."Store re?ts and product revolutions have proven to be false dawns. In a fast-changing retail environment M&S has suffered from a last mover disadvantage and legacy of under-investment," Exane said.However, the broker said that "this is changing": "Life beyond recent investments is in sight".Analysts explained that the company's eCommerce solution will be launched within a year and supply chain improvements are expected to go live. Meanwhile, growth in Food and overseas should also result in a strong uplift to profitability. "M&S is striking at the heart of recent difficulties."The broker said these changes could drive a reversal in recent negative earnings momentum with profit expected to jump 40% over the next three years.The stock was trading 2.16% higher at 491.3p by 14:54 on Thursday.BC