Utilize your financial knowledge, give your answer or opinion to the input question or subject . Answer format is not limited.

Are the stocks of competitor companies negatively correlated?
Not especially. It depends on why sales have changed. If it's just consumer demand, that affects everyone in parallel rather than pushing in opposite direactions. If it's changes other than sales, that may have no effect on other companies. If it's because someone introduced the next must-have-it device and they're selling rapidly and drawing customers from the competing brands, maybe. And that's all neglecting the fact that this may already have been incorporated into the competitor's share price long ago, in anticipation of this news. Sorry, but the market just ain't simple.