A 19 percent attendance boost and reduced losses from discontinued operations helped Six FlagsEntertainment Corp. narrow its fourth-quarter loss, the theme park company said Tuesday.

For the period that ended Dec. 31, Grand Prairie-based Six Flags reported a net loss of $94.3 million, down from a $115.5 million net loss a year ago, when the regional theme park operator was still in bankruptcy. The quarter included $2.5 million in reorganization expenses, down from $16.2 million a year ago.

Six Flags’ shares spiked in early trading, posting a 52-week high of $64.49. But the stock gave up those early gains and then some, closing off 2.5 percent, or $1.54, at $60.96.

Adjusting income from continuing operations to exclude items such as accounting changes, income taxes and restructuring costs, the company had a record $22 million in adjusted earnings before interest, taxes, depreciation and amortization — a broad measure of profitability known as EBITDA.

Fourth-quarter revenue was $122 million, up 20 percent over the year-ago period, based largely on increased attendance and in-park sales.

For the full year, the company swung to a $598.9 million profit from a $229.2 million loss in 2009. Revenue increased $77 million,  or 9 percent, to $976 million, and income from continuing operations rose.

“We had a fantastic ending to a great 2010,” Jim Reid-Anderson, chairman, president and chief executive, told analysts. “I look back with pride at all we accomplished at Six Flags in the past year.

“We successfully emerged from Chapter 11, transitioned to a new senior leadership team, improved our credit ratings [and] refinanced our debt.”

Six Flags theme parks hosted 3.1 million visitors in the fourth quarter, due largely to the October “Fright Fest” and December “Holiday in the Park” programs.

Full-year attendance of 24.3 million guests rose 4 percent from 2009. Per-guest spending in the fourth quarter of $39.75 was a nearly 2 percent increase. For the year, per-guest spending of $40.18 was up 4 percent, or $1.55.

Next month, Six Flags will celebrate the launch of its 50th anniversary season. On Aug. 5, 1961, Texas businessman Angus G. Wynne Jr. opened Six Flags Over Texas, making the Arlington attraction the world’s first regional theme park, according to the company.