United Continental Holdings, Inc. on Thursday reported its net income plunged 23.4 percent year over year as fuel expenses and merger-related costs weighed down its performance.

The Chicago-based airline recorded net income of $653 million versus pro forma net income of $852 million a year ago, including $120 million in costs related to the integration of United Air Lines and Continental Airlines, according to a company statement. This earnings period marks the company's fourth quarter of combined results since their merger in October 2010.

Operating expenses jumped 11.6 percent to $9.24 billion with fuel costs up by $1 billion, or 41.3 percent, year-over-year.

Total revenue increased 8.7 percent to $10.2 billion as passenger revenue rose 9.2 percent to $9 billion and cargo revenue slid 2.4 percent to $283 million.

United Continental also reported progress in its integration of the two airlines and said it was on track to achieve a single operating certificate by the end of 2011.

United Continental shares fell 1.13% to close at $20.11 in Thursday trading.