IPS is only about half of the incorporated city, so the IPS district is not that much larger than Ft. Wayne in total. I don't know how many charters there are in Ft. Wayne, but they have been opening about 5 a year in Indy. But it seems like a lot of them fail. This year was huge. They took three of the biggest high schools (Arlington, Howe, and Manual) and gave them to charters. That is why Ft. Wayne would have popped up on top this year. That's probably 4000-5000 students moved to charters in one year.
Of course that Charters can cherry-pick students and send back the ones they don't want. Charters don't have to bear the cost of Special Ed, they get the buildings for free, and the new Indiana laws allow charters to have half of their staff with no teaching credentials at all. The for-profit charters can literally hire dozens of "teachers" at near minimum wage.
What could possibly go wrong?
(I think one of those charters is technically a not-for-profit, but that doesn't really matter. It is still a for-profit business baying handsome salaries to the key execs. Not-for-profit is just an accounting gimmick.)