Barclays upgraded Marks & Spencer to 'equalweight' from 'underweight' and pushed the target price to 600p from 390p following the company's full-year results on Wednesday."While we are still concerned with a long lasting trend of market share losses in General Merchandise, which we consider structural, we recognise a benign gross margin and returns outlook over the next three years which no longer warrants our negative stance on earnings," said Barclays.With M&S returning to pre-tax profit growth after four years, Barclays said the critical question now is whether this is an inflection point in the company's future profitability.Although it recognised that M&S has shown visible improvements versus its past, Barclays was hesitant to become more bullish at this stage, noting that the retailer is yet to stop lagging some of its peers, like Next.Barclays raised its 2016 earnings per share estimate to 35p from 33p and its estimate for 2017 to 37p from 34p.