I wouldn't be surprised if the marketing budget is huge for this. They been advertising it for months on end everywhere.

Gross refers to gross earnings in U.S. dollars. On average, the movie's distributor receives a little more than half of the final gross (often referred to as the "rentals") with the remainder going to the exhibitor (i.e., movie theater). The money split varies from movie to movie, but, generally, the contract favors the distributor in early weeks and shifts to the exhibitor later on.

Production Budget refers to the cost to make the movie and it does not include marketing or other expenditures.

Mismanagement of resources (Not even relating to production) can make a movie go up dramatically. 

The Mermaid isn't a Sony Pictures film its a Chinese film that was distributed by Sony Pictures is couple of markets outside China but since it pretty much made all its money at the box office in China.  Sony didn't really make anything worth mention from it.

https://en.wikipedia.org/wiki/The_Mermaid_(2016_film)

Sony Pictures pretty much put all their eggs this year into Ghostbusters and that pretty much bombed.

Apparently the movie had reshoots. Would all that be included in the production budget? 

That number sounds unreasonably high, unless it means to include the home video sales, digital media downloads and prodits from promotional products.

Did they completely mismanage their expenses? There are a lot of movies with big budgets and large marketing campaigns which fall well below the 750M target and are considered successes.

Anyways, Suicide Squad should do just fine. If a 65M Friday night makes you panic, either you need to spend more wisely or learn the Art of Zen.

They are spending way too much money on these movies.

It'll probably make its money back, Will Smith is still a big star worldwide and that will help, but the script of the movie is so hilariously bad, the people shitting on Ghostbusters and pinning their hopes on this as being some shining example of summer movies played themselves. This script is probably worse overall and you can tell they completely chopped the film apart in the editing room. The Joker is pointless in the film as are 2-3 other main characters too.

500mi from Ghostbusters and now 800 from Suicide Suqad, it seems to me movie companies are trying to pull a move to avoid paying taxes, that can´t be how hollywood do business.

also, why hire Will Smith? It is a super hero movie, put a bunch of unknows to save cost, they will become stars afterwards anyways.

Why would they spend that much on it?

The estimated budget is roughly $175-$200 million. Why does it need to gross 4x its budget in order to break even?