Shorters... Good luck!, page-797

Black rock doesn't need to buy back the shares. They can request to have their shares returned. In another words, those that borrowed to short have to buy back shares from open market to close their short positions. Then return the borrowed shares to black rock.

If blackrock doesnt request to have the shares returned, the shorters don't need to return but they will be counting paper losses and likely margin calls if the share price of gxy goes up.

With a major news like this coming up, I can't see the price staying down. Let's see what insto like black rock will do.