CMC Markets Plc (LON:CMC) is the latest spread bet firm to warn that changes to rules governing customer trading have hit it harder than expected.
Revenues for the year from CFD and spread betting operations will drop by 37% to US$110mln, while net operating income will be US$131mln.
Costs are also running higher than expected.
There are signs that the disruption caused by the new European rules is stabilising, said CMC, while client money has remained strong, and active client and new client numbers have remained stable.
Shore Capital says CMC ran at a loss in the second half of the year and has chopped its profits forecast for the year to £6-7mln from £19mln.
The broker added that although CMC said it expects to meet the market consensus figure for 2020, this number keeps reducing after each trading statement.
Grant Foley is also stepping down as chief financial officer and chief operating officer, said CMC.
Shares fell 7% to a new low of 77.5p.