Citigroup Inc. cut its operating expenses by 2% during the third quarter to $10.2 billion, the lowest level so far in 2017, helping the New York-based banking giant lower its efficiency ratio and boost its operating leverage.

The company's executives in recent months had vowed to improve efficiency and bolster operating leverage in the second half of this year. It delivered with the third-quarter results on Oct. 12 — as costs dipped, revenue climbed 1.5% during the period. And Citi reported an efficiency ratio of 56%, down from 59% the previous quarter and better than the 58% that the company has targeted for all of 2017.

Executives, speaking on a call with analysts, credited a long-running culture of cost control that dates to the aftermath of the financial crisis.

Citi was badly bruised at the time, but it moved aggressively to cordon off and either sell or wind down troubled and noncore assets to minimize the drag on expenses and the company's profits. Executives said that, while the worst of the crisis' aftershocks are well behind Citi, the company continues to wind down unwanted legacy assets as well as focus on ongoing efficiency efforts such as containing real estate and staffing expenses.

"That discipline is not something that we let slip away, and that's a discipline I expect we'll continue to keep as we go into the future," CFO John Gerspach said on the call.

The cost control helped lift Citi's bottom line.

Third-quarter net income applicable to common shareholders rose to $3.86 billion, or $1.42 per share, from $3.62 billion, or $1.24 per share, a year earlier. The third-quarter result bested the S&P Capital IQ consensus EPS estimate of $1.30.