The five U.S. global trading and universal banks reported strong investment banking and weak trading results during the fourth quarter of 2017, a trend that is unlikely to reverse anytime soon, according to report published Wednesday from Fitch Ratings.

Growth in both debt and equity underwriting, and in the financial advisory business, boosted investment banking results. Investment banking revenue was up by 19.2% year over year in the fourth quarter, recording its best result in five years, the report says.

However, the big banks’ total capital markets revenues actually declined by almost 11% year over year due to weakness in fixed income, currencies and commodities (FICC) net revenues, “as client engagement levels fell across multiple products.” Overall, FICC revenues are down 30.7% year over year, the report says.

“Low volatility is problematic for trading, but it does allow corporates to plan for M&A activity which boosts investment banking results,” says Justin Fuller, senior director at Fitch Ratings, in a statement. “Though, the correlation between guidance during earnings calls and future revenue is weak as economic and political variables can often delay deal execution.”

Capital markets revenue declined as a percentage of total revenue for each of the large Wall Street firms, the report says, with its average share of overall revenues coming in at 22.1% in the quarter, down from 24.9% in the same quarter in 2016.

At the same time, the big firms all had “significantly higher net interest income this quarter due to higher year over year short-term interest rates as well as incrementally higher wealth/asset management revenues amid higher global equity markets,” the report says.