Activist hedge fund Jana Partners is stepping up pressure on Six Flags Entertainment, urging the amusement park operator's board to appoint an investment bank and investigate a potential sale of the business, according to a report by the Wall Street Journal.

The renewed campaign follows disappointing second-quarter results from Six Flags, which reported a net loss of $202.6m, more than double the $99.6m loss recorded in the same period a year earlier.

Jana has been an activist investor in Six Flags since last year and has previously pushed the company to consider strategic alternatives alongside operational changes. The New York-based fund built an economic interest of roughly 9% alongside co-investors, according to reports at the time.

Its earlier campaign called for improvements to Six Flags' marketing and visitor experience, technology investment and changes to management, while also advocating that the company examine a potential sale.

The latest intervention comes as Six Flags continues to work through a turnaround against declining attendance and rising costs. The company has sought to streamline its portfolio, including disposing of non-core parks and closing a Maryland location after the 2025 season.

Jana's call for an investment bank would give Six Flags a formal process through which potential strategic and financial buyers could assess the theme-park operator. There is no indication that Six Flags has agreed to launch a sale process.

The activist's involvement in Six Flags has also included an unusual collaboration with Kansas City Chiefs tight end Travis Kelce, who joined the investor group and subsequently agreed to become a Six Flags brand ambassador, according to reports.

The campaign represents one of several recent activist situations pursued by Jana Partners. The hedge fund has also targeted Cooper Companies, calling for a new chief executive and urging the medical-device maker to consider strategic alternatives including asset sales.

Jana has also taken a position in payments company Fiserv and pushed for measures aimed at improving the company's share-price performance.