German to English Bus/Financial Finance (general)

This German term is relatively rare, and it relates–at least, in part–to the CumEx tax scandal across several European nations. Short sellers sold shares to buyers when the short sellers did not actually own the shares (and thus had to borrow them). The short sellers would borrow shares from large institutional investors, like banks or insurance companies, around the record date. It would then appear to the tax authorities that two entities own the shares, though in fact only one does. Tax credits and tax refunds result from this and governments are cheated out of billions in tax revenue. The party who lends the shares to the short seller is called the "Stückgeber". I have translated this as "donor," but I'm not sure if this is adequate. Maybe "share donor"? Any recommendations?

Sample sentence:
Die Eindeckungsgeschäfte wurden schuldrechtlich über Aktien abgeschlossen, die keinen Dividendenanspruch mehr beinhalteten („Ex-Aktien”) und in den abgeurteilten Fällen regelmäßig aus dem Bestand von großen institutionellen Anlegern, den Stückegebern.

The replacement transactions were completed on shares under the law of obligation which no longer had a dividend right (“Ex-share”) and in the condemned cases regularly came from the portfolio of large intstitutional investors, the donors.

Here is a very thorough journalistic piece on the problem.
https://www.handelsblatt.com/finanzen/banken-versicherungen/...