JP Morgan has kicked off Wall Street's earnings season with a first-quarter performance that topped analyst expectations thanks to 20%-plus rises in underlying revenues from investment banking as well as equities and fixed income trading.

A strong showing on several fronts in the first three months of 2015, including the best quarter for fixed income sales and trading in almost two years and the best for equities in six years, helped drive net profits at JP Morgan's corporate and investment bank up 19% from a year earlier.