Why very high rates rarely last

Very high rates are usually promotions with a small cap, or a DeFi pool that just got token rewards: as money pours in, the rate thins out or the promotion sells out.

YieldCompanion labels a product "Rate spike" when its rate is 50% a year or more, or has just risen 2-fold within 7 days (once at 15% or more). The label is a warning only; a labelled product is never picked as a suggestion.