The FCA had more than 500 cases open at the start of April, which is nearly 100 more than the same time last year.
According to a Financial Times report, the regulator had a record 504 investigations open as of 1 April, compared with 410 the year before.
Of that caseload, 85 cases are looking into suspected financial crime and 75 are focused on insider dealing.
It is looking into 61 cases related to governance or culture problems, compared to just 15 cases in that area in April 2017.
The FT says FCA statistics show the high number of cases has not led to increasing fines. In fact, penalties are at seven-year lows.