Exane BNP Paribas has cut its recommendation for insurance group Aviva from 'outperform' to 'neutral', saying it sees limited upside after a strong run recently.The broker said that the share price has increased significantly under new management after the firm's interim report given the cost savings made the in the first six months of the year.However, profits remain challenged by weaker flows and declining revenue margins, with UK and Europe unit-linked revenue margin falling by more than the cost decline in the first half.Exane said: "We struggle to see the top line growth needed to secure the 2015 consensus earnings forecasts and the price-to-earnings multiple is not cheap in a historical relative context. "While we expect Aviva should outperform Legal & General, we prefer Standard Life, where we see significant operational leverage from the Investments business."While the target price for the stock has been lifted by 6.0% to 403p, the broker pointed out that its earnings forecasts are significantly below the consensus level for 2015.The share price was down 1.16% at 399.6p by 11:36 on Friday, having gained around 10% over the last month.BC