Nothing at all wrong about that. Be careful that especially before big news, it's rather common that there are huge swings because (a) the market makers pull/widen their quotes, (b) others already do what you are describing and (c) other actors try to exploit the situation by moving the market in one direction chosen at random and taking the profit before the actual news hits, so it doesn't even matter to them which side they bet.
If you spot your pattern you can't know for certain if the cause is actual insider trading or (c) amplified by (b). You don't know, so you take an educated guess and make a bet. That's trading, not insider trading.
Edit: It would possibly be a slightly different case if you could write software that identifies insider trades with a 100% guarantee, which nobody else has been able to do so far. In that case sell it to market regulations or the DOJ for a few millions and retire early and risk free.