a vested interest — personal stake (often hidden or self-serving)
collocationC1IELTS 7+neutraloccasional
a strong personal reason for wanting something to happen, especially because you will get an advantage or benefit from it, sometimes at the expense of others.
Say it like a native
Textbook They possess a personal pecuniary interest in the outcome.
Native They've got a vested interest in the outcome.
'Pecuniary interest' is legalese; 'a vested interest in' is the natural idiom.
Pattern: have a vested interest (in something)
In use
- The committee members all have a vested interest in the outcome of the decision.work
- In my opinion, when politicians have a vested interest in certain industries, it can lead to biased decisions that do not benefit the public as a whole.IELTS speaking
Common mistake
✗ He has a vested interest on the deal.
✓ He has a vested interest in the deal.
'A vested interest IN something', not 'on'.
Common collocations
a vested interest in— in, have, such, those with
Don't confuse it
Unlike the general word 'interest', 'a vested interest' implies a personal benefit or hidden motive, not just curiosity or involvement.