Goldman Sachs Group on Thursday posted a sharp drop year on year in its fourth quarter profit, but the result still exceeded Wall Street estimates.

The bank's net earnings in the fourth quarter of 2013 slumped 19 percent to 2.33 billion U.S. dollars on a yearly basis, according to an announcement released before Thursday's opening. Diluted earnings per common share were 4.60 dollars in the quarter, compared with 5.60 dollars in the year-ago period.

Its net revenue also fell 5 percent to 8.78 billion dollars in the fourth quarter, the bank said.

Analysts had expected the bank to report diluted earnings per share of 4.22 dollars in the fourth quarter on 7.71 billion dollars in net revenues, according to a consensus estimate from Thomson Reuters.

Two segments in the New York-based investment bank largely contributed to the falling earnings, with net revenues in Fixed Income, Currency and Commodities Client Execution, and institutional client equities services, tumbling 15 percent and 27 percent, respectively.

These trading activities have been increasingly affected by the so-called "Volcker Rule," a key financial regulation in the aftermath of the latest global financial crisis, which strictly restraints banks'risk trading, such as proprietary trading.

In 2013, the company staged a modest gain in both net revenues and profit, standing at 34.21 billion dollars and 8.04 billion dollars, respectively, compared with 34.16 billion dollars and 7. 48 billion dollars in the preceding year.

Goldman Sachs shares added losses in the morning trading, weighing down the blue-chip Dow Jones Industrial Average.

So far, five of the six major U.S. banks had released fourth- quarter earnings reports, with JPMorgan Chase & Co., Wells Fargo & Co., Bank of America, and Citigroup among them, depicting a mixed picture of banking sector's new earnings season.

Morgan Stanley would be the last of the six banks to reveal its earnings, slated for Friday.