Yes, EQUITIES is a Scrabble word!

Letter values in Scrabble US: E 1, Q 10, U 1, I 1, T 1, I 1, E 1, S 1.

Is it a valid word?

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

the difference between the market value of a property and the claims held against it
the ownership interest of shareholders in a corporation
conformity with rules or standards