hubieron asegurado
-they/you had assured
Antepréterito para el sujeto ellos/ellas/ustedes del verbo asegurar.

asegurar

Cuando hubieron asegurado la pesca, ambos barcos estaban tan cargados que corrían peligro de hundirse.
When the catch was secured, both the boats were so heavily laden that they were in danger of sinking.
Palabra del día
travieso