Merlin, which also owns theme parks such as Alton Towers and Chessington World of Adventures, said market conditions in the capital remained challenging despite recent favourable movements in foreign exchange rates.
Group trading in the year to date was broadly in line with expectations, reflecting the continuation of the key trends underlying the 2015 result.
Merlin said new rides and features opened so far this season had been well received.
It said new accommodation was progressing well, with an extension of the Legoland Deutschland Holiday Village already open, and further developments at Gardaland, Chessington World of Adventures and
Warwick Castle set to open in coming weeks.
Merlin is reportedly facing a multi-million pound fine after pleading guilty to breaching health and safety law last month following an accident at Alton Towers last year.
Two female passengers on the Smiler ride suffered leg amputations and three others were also seriously injured when their carriage collided with a stationary carriage on the same track in June.
Shares fell 10.5p, or 2.4%, to 420.9p in early London trading.