Yes, OLIGOPOLIES is a Scrabble word!

Letter values in Scrabble US: O 1, L 1, I 1, G 2, O 1, P 3, O 1, L 1, I 1, E 1, S 1.

Is it a valid word?

OLIGOPOLIES is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

(economics) a market in which control over the supply of a commodity is in the hands of a small number of producers and each one can influence prices and affect competitors