Merlin, the owner of Alton Towers, expects a drop in annual earnings for its theme parks business by as much as £47 million this year following a roller coaster crash at the Staffordshire park.
The group said the crash has had "an adverse impact on trading at the start of the critical summer period" as well as for its financial performance for the full year, and could also hit results next year.
Underlying earnings for the theme park division are expected to fall from £87 million in 2014 to between £40 million and £50 million this year.
The financial implications are a result of an accident which caused five people to be seriously injured on June 2.
Following the crash, the park was shut for four days, along with a suspension of theme park marketing and further ride closures due to health and safety concerns.
Two of the victims of the crash, Leah Washington and Vicky Balch, had a leg amputated below the knee as a result of their terrible injuries.
Leah's boyfriend, Joe Pugh, suffered two shattered knees and has lost the use of one of his fingers.
However, the group, which also operates attractions such as MadameTussauds and Legoland parks, is expected to see profit before tax "broadly in line" with last year at £249 million after savings in financing and othercosts.
Despite Merlin's International parks achieving a strong financial performance, the London sites were hit by lower visitor numbers.