Artificial Intelligence Technology Solutions Inc (AITX)

[kabblooi]

I'm new to the investing world, so I hope I don't sound too dumb when I ask this: how is it that shares can be bought, but the price goes down? I figured it was a supply vs. demand deal, so if shares are bought, less shares are available, so the price would go up. I'm assuming there's some factors involved that modify this way of thinking, or am I completely wrong in my thought process?