selloff vs cut-rate sale

selloff and cut-rate sale both are nouns.

Word	Noun	Adjective	Verb	Adverb
selloff	Yes	No	No	No
cut-rate sale	Yes	No	No	No

As nouns, cut-rate sale is a hypernym of selloff; that is, cut-rate sale is a word with a broader meaning than selloff:

selloff: a sale of a relatively large number of assets (stocks or bonds or commodities) at a low price typically done to dispose of them rather than as normal trade
cut-rate sale: an occasion (usually brief) for buying at specially reduced prices

Other hypernyms of selloff include sale, sales event.

selloff (noun)	cut-rate sale (noun)
a sale of a relatively large number of assets (stocks or bonds or commodities) at a low price typically done to dispose of them rather than as normal trade	an occasion (usually brief) for buying at specially reduced prices