$VG S&P 500(VOO.US)$Invesco QQQ Trust(QQQ.US) The stock price dropped again because the weekend negotiations failed. Next, we'll watch to see if the conflict escalates or if Taco gets back on track. The current drop isn't too big; the market should have already cleared the first wave of panic selling, and it's clearly pricing in a return to normalcy.

If you trade stocks based on news now, you'll end up buying high and selling low, losing money like a fool. It's really better to focus more on valuation levels—buy when you think it's cheap, and consider releasing some cash when it's expensive. News can only be used to judge why it's rising or falling; don't easily extrapolate linearly.

Actually, there's no need to be too afraid of war. Those interested can look up the index trends in the US and UK during WWII and the Gulf War. The truly scary drops were during the high-valuation period of the Millennium Internet crisis.