Is it best to sell stocks before or after quarterly reports?

I think Jansen pretty much explained the typical reactions of stock movement towards quarterly reports. To value add to his point, I think its pretty interesting to see how market reacts to companies that have been forecasted to peform poorly. I want to bring up Snapchat's price actions against their quarterly report aka 10Qs.

For Snapchat, their recent quarter results sent stocks soaring 22% purely from after-hours trading, despite DAUs has been shrinking consistently. The company ended the year with 186 million daily users, down from 187 million users a year earlier.

To quote, "But the number was the same as it had in the third quarter of last year, marking the first time in three quarters that Snap’s daily user count hadn’t fallen."

Of course, rev growth and EPS losses were better than expected, but it was still interesting to see immense capital gains potential from a stock with consistent negative sentiment.

Recent earnings call for Grubhub was also pretty interesting. 10Q results was taken up with dissapointment with a immediate steep selloff of -20%, missing multiple analysts projections and prev quarter's guidance. However 1 day later investor earnings call address managed to spin $GRUB was on track in their growth plans, resulting in a delayed correction in stock price back to initial levels.

Note the sharp drop, near the bottom was the investor earnings address.

This is a really interesting question, I don't have an answer for that actually but here's another thought for you.

If I had the time and money, something that I would do is to gather all the Ex-Dividend date and closing price, match it with the dividend paid so as to attain the general trend of whether the magnitude of decrease in price (if there is the occurence of one) of Ex-Dividend stocks is higher or lower than that of the dividend being paid.

There are some counters that simply have no movement despite it being and XD counter. Definitely a statistic I would like to find out. If there is a system of such power, it can certainly gather data on FY announcement and monitor how prices move in relation to the reports