The Grand Prairie, Texas-based company said earnings rose to $66.3 million, or 67 cents per share, from $47.4 million, or 47 cents per share, in the same quarter a year ago.
The amusement park operator said revenue increased 3.5 percent to $376.6 million from $363.7 million in the same quarter a year ago, and missed Wall Street forecasts. Analysts expected $396.6 million, according to Zacks Investment Research.
Six Flags shares have climbed $4.18, or 11 percent, to $41 since the beginning of the year. The stock has risen $5.15, or 14 percent, in the last 12 months.