borrow against
phrasal verb with borrow verb [ I or T ] uk/ˈbɒrəʊ/ us
[ I or T ] FINANCE, BANKING
to borrow money and agree to give valuable property to the organization who has lent it to you if you fail to pay it back:
They borrowed against their stock portfolio so they could buy 36 acres from a local farmer.
They borrowed £55,000 against the property, then valued at £225,000.