According to this article https://www.faz.net/aktuell/finanzen/bafin-verdaechtigt-ft-j... there is an investigation in insider trading related to the Ft-article series (naked short selling allegedly rose before the publication of the articles)
Insider trading is illegally profiting on information that was given to you in trust, while naked short selling is short selling without a documented ability to deliver the stock.
As far as I can gather from english language articles, the regulator has banned short selling in response to an article alleging fraud at wirecard. Bloomberg describes this as "unprecedented".
https://www.bloomberg.com/news/articles/2019-02-18/bafin-ban...
'Al Alam Solutions, a Dubai-based payments processor with skeletal operations in the Emirate, is the largest of the three “partner” entities. Wirecard refers clients to Al Alam in return for a share of any processing fees as commission. A former Al Alam employee said the business had six or seven staff in total and “the boss” was Oliver Bellenhaus, a Wirecard executive. The other partners are PayEasy Solutions, a Philippine payments group that shares an office with a Manila bus company, and Singapore-based Senjo. '
https://www.ft.com/content/a7b43142-6675-11e9-9adc-98bf1d35a...