death knell

Translations
предзнаменование конца
The fall in sales sounded the death knell for the company.
Падение продаж прозвучало как предзнаменование конца для компании.
Definitions
A death knell is a sign, event, or sound that signals the end or failure of something, often used metaphorically to indicate the impending demise or destruction of an idea, institution, or situation.