 And the week ends up on Friday with the producer price index. Six Flags Great Adventure is marking its 50th anniversary by finalizing an $8 billion merger with Cedar Fair. That's the Ohio-based parent company of Dorney Park, a popular amusement park near Philadelphia. The combined company will operate under the Six Flags name. It now includes 27 amusement parks, 15 water parks and resorts in 17 states, plus Canada and Mexico.