Is there a tool that matches price changes with material events?

I'm researching a stock and see a ~20% drop in share price during one month of 2017. Clearly something happened to cause this such as a dividend change or write-down. I would rather not spend too much time searching for this.

Is there a tool that will let you look at a stock over time and also show material events from the past? Finviz is great but does not go back very far with news stories.