The biggest French bank, BNP Paribas, on Friday said net profit slid by 44.8 percent in the first quarter hit by poor investment bank revenue and a sluggish economy in Europe. In the January to March period net profit fell to 1.59 billion euros ($2.06 billion), but beat analyst expectations of a 1.4-billion-euro after tax profit. Retail banking held up well over the period, the bank said, but the investment and corporate banking unit suffered badly, with revenue down 21 percent. Results were also affected by a one off boost in the same period last year when BNP Paribas sold off a stake in the real estate firm Klepierre. BNP Paribas has undergone a major restructuring to meet capitalisation rules intended to ward off a repeat of the 2008 financial crisis. The banks core tier one ratio -- the proportion of super safe assets in relation to riskier ones -- stood at 10 percent at the end of March. Germany\'s Deutsche Bank, by way of comparison, stood at 8.8 percent. ---Dow Jones Newswires contributed to this report ---