I'm not comfortable at all with that kind of prediction, but I'm betting on a drop of the market of at least 10% before the end of the year.
Positive view: A vaccine (highly improbable on the short term, and even if there's a vaccine, it won't be accessible for everyone in a short period).
Negative view: A pandemic that will continue at least until the end of the year, killing tourism and many small shops (highly probable until december).
Restaurants and bars are being reconfined in many places. I think that my prediction comes from these news.