Correct. Walter was part of the 3 person team together with Gretchen and Elliot. He was, correction: is, a really smart chemist.
Back then the company wasn't worth that much. And because Skyler had a baby coming, Walter (as he explained to Jessie in Buyout) sold out his share of Gray Matter for a measly 5000 bucks. Big mistake, because a few years later, the company was worth billions, with a B.
Apperently the story was completely different from what I perceived of it.
Around 20 years ago, Walt worked in Application Labs ("Cancer Man"). He also worked in a chemical lab near Los Alamos, and met Skyler White, a hostess at that time, in a restaurant ("Cancer Man"). He moved to Albuquerque to work for Sandia Laboratories just prior to his firstborn ("Full Measure").
I guess it's time for a Breaking Bad marathon.