Yes, PORTFOLIOS is a Scrabble word!

Letter values in Scrabble US: P 3, O 1, R 1, T 1, F 4, O 1, L 1, I 1, O 1, S 1.

Is it a valid word?

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

a large, flat, thin case for carrying loose papers or drawings or maps; usually leather
a set of pieces of creative work collected to be shown to potential customers or employers
a list of the financial assets held by an individual or a bank or other financial institution
the role of the head of a government department