Online retail broker Plus500 reported a decline in revenues during the second quarter of the year and said for the full-year its margins would be "significantly" lower but revenues to be "similar" to 2014 as it invests to acquire new customers. The Israel-based company put the slight dip in sales down to quieter markets and the temporary suspension of its UK business following an anti-money-laundering checking process by the UK financial regulator.Plus, which remained cautions on trading levels and market volatility, said it continued to be subject of a "high level of regulatory scrutiny" following the probe but expects the onboarding of new customers in the UK to recommence in August. It said 19,337 new customers joined in the second quarter.Liberum, its house broker, said back in May it expected between a third and half of customer to leave - but the AIM-listed company said it had 93,267 active customers during the half-year, down 12% from the 105,976 in the previous full year.As a result, revenues during the second quarter fell slightly to $44.9m from $45.5m in the first, meaning the first half showed a 19.5% increase in revenue to $127m compared to the same period last year.The $2m of one off costs related to the regulation and remediation process of Plus's UK arm and the increased marketing spend coincident with the trading difficulties in the UK drove EBTDA margins to its lowest quarter since the company's 2013 initial public offering.Chief executive Gal Haber said: "The investment which we continue to make in the Plus500 brand and infrastructure has proved its value during the recent period of disruption during which we traded profitably in each month."Our superior proprietary technology and continued investment in the business position us well for continued profitable trading."Shares were up 0.19% to 386p on Thursday at 10:32.