US banking giant Citigroup (NYSE: C - news) reported a big jump in quarterly earnings Thursday, as lower expenses more than compensated for weakness in bond trading and some other businesses.

Earnings for the third quarter were up 51 percent at $4.3 billion. Revenues fell 5.1 percent to $18.7 billion.

A big factor in the earnings jump was a huge decline in expenses compared with the year-ago period, when heavy litigation and restructuring costs weighed on results.

Like other large banks, Citigroup suffered from lower revenues in bond trading, partially offset by higher revenues from equity trading. Investment banking revenues also fell, further denting operating earnings in the institutional clients group.

In global consumer banking, Citigroup's other large division, lower revenues were partially offset by a drop in operating expenses.

"The quarter had more than its fair share of volatility and our results speak to the resilience of our franchise globally," said Citigroup chief executive Michael Corbat.

"And despite revenue headwinds, we once again proved our ability to manage our risk, our expenses and our capital."

Citigroup earnings translated into $1.35 per share, seven cents above analyst expectations.

Citigroup shares rose 3.1 percent to $52.29 in pre-market trade.