Investment manager 3i Group said all its businesses had performed well in the year to end of March, although it warned of currency volatility across many financial markets.The FTSE 100 group reported a total return of 19.9% equivalent to £659m, in the 12 months to 31 March; a 4.6% increase year-on-year.3i, which operates in equity, infrastructure and debt management, said its operating expenses declined 3.7% to £131m, while operating cash profit for the period jumped to £28m from £3m in 2014.The group reported a 20% gross investment return on its infrastructure arm, which benefited from a 25% total shareholder return from 3i Infrastructure, the strongest performance since the company's initial public offering.However, the London-listed company issued a warning over the increased volatility in a number of markets."Many financial markets are at or near all-time highs and currencies are subject to increased volatility," said group chairman Adrian Montague."We are focused on enhancing the value of our existing investment portfolio as well as pursuing investment opportunities if the strategic and financial case is strong."3i shares were up 2.25% to 523.50p at 09:04 on Thursday.