Question: Tax research Case

Dt Corporation runs a chain of dry cleaners. Boric oxide is used heavily in Dt's dry cleaning process and has been in short supply several times in the past. Dt Corporation buys a controlling interest in Dig Corporation - a boric oxide mining concern. Dt's sole reason for purchasing the Dig stock is to assure Dt of a continuous supply of boric oxide if another shortage develops. Although boric oxide must be refined before it is usable for dry cleaning purposes, a well-established commodities market exists for trading unrefined boric oxide for refined boric oxide. After owning the Dig stock for several years, Dt sells the stock at a loss because Dig is in difficult financial straits. Dt no longer needs to own Dig because Dt has obtained an alternative source of boric oxide.

What is the nature (character) of Dt's loss on the disposition of the Dig Corporation stock? When and where can it be deducted, if at all?