horse trading vs horse-trade

horse trading is a noun but horse-trade is not a noun.

Word	Noun	Adjective	Verb	Adverb
horse trading	Yes	No	No	No
horse-trade	No	No	Yes	No

horse trading (noun)	horse-trade (noun)
the swapping of horses (accompanied by much bargaining)
negotiation accompanied by mutual concessions and shrewd bargaining

horse trading (verb)	horse-trade (verb)
	negotiate with much give and take