Revenues from consumer lending collapsed from £217.2m to £77.3m in 2015, with Wonga blaming "stricter lending criteria" and the introduction of a regulatory price cap.
The comments refer to the Financial Conduct Authority's ruling that now requires customers to go through stricter affordability checks and the introduction of a 0.8% cap on the cost of payday loans on the amount borrowed per day.
However Andy Haste, Wonga's chairman, was bullish.
He said: "We expect 2016 to mark a turning point in our financial performance. With further funding planned for later this year, we're now in a position to move back into growth in 2016 and expect to return to profit in 2017."
Wonga has faced a barrage of criticism over the high interest it charges on its loans and it has been accused of targeting those who are vulnerable.
Haste added: "We continued to focus on changing our culture to ensure customers are at the heart of our business, while strengthening our financial position."