Both stocks had a good run last year but travel and gaming news is unlikely to be as supportive in the first half, says analyst Jaafar Mestari.
The hotel industry is unlikely to throw up positive surprises, especially in the USA, he added.
There the "real" RevPAR (revenue per available room) is already 6% above its 2008 peak and is now the only region showing accelerating supply.
The broker has downgraded TUI and Ladbrokes to 'neutral'.
"An environment of stable wage inflation and slightly higher food inflation than in 2017 should allow organic growth rates towards the high end of the sector's historical range, and stable margins," it said.
Ladbrokes shares shed 1.46% to 183.375p, while TUI lost 0.03% to 1,577p.