Low-cost carrier Spirit Airlines Inc on Wednesday reported a higher-than-expected quarterly profit, helped by increased airfares and fees for baggage and other services.

Shares of Spirit rose 6.3 percent to $45.75 in trading before the market opened.

Net income nearly doubled to $61.1 million, or 84 cents a share, in the third quarter, compared with $30.9 million, or 43 cents a share, a year earlier.

Excluding special items such as costs tied to the sale of stock by certain shareholders and fuel hedge adjustments, the profit was 79 cents a share. Analysts on average were expecting 75 cents, according to Thomson Reuters I/B/E/S.

Revenue rose 33 percent to $456.6 million. Of that, $177.1 million came from fees for optional services.

Operating costs climbed about 23 percent in the quarter.

Spirit, based in Miramar, Florida, is a growing carrier that offers lower base airfares but charges extra for a host of products, including carry-on and checked baggage, assigned seats and snacks.

The company had more departures and flew fuller planes in the seasonally strong third quarter, which includes summer vacation travel. Fares were also higher, with average ticket revenue per flight segment rising 15 percent to $82.84.

Reporting by Karen Jacobs in Atlanta. Editing by Lisa Von Ahn.

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Photo Credit: Spirit Airlines' 319 jet lands at the San Diego airport. Ian Gratton / Flickr