short selling vs trading

short selling and trading both are nouns.

Word	Noun	Adjective	Verb	Adverb
short selling	Yes	No	No	No
trading	Yes	No	No	No

As nouns, trading is a hypernym of short selling; that is, trading is a word with a broader meaning than short selling:

short selling: sale of securities or commodity futures not owned by the seller (who hopes to buy them back later at a lower price)
trading: buying or selling securities or commodities

short selling (noun)	trading (noun)
sale of securities or commodity futures not owned by the seller (who hopes to buy them back later at a lower price)	buying or selling securities or commodities