The concept of market prices experiencing a rapid and significant decline is commonly referred to as a "steep decline". This phenomenon can be observed when the prices of various assets decrease at a fast pace, causing concern among investors. This is often seen as a sign of market instability and can be a result of various factors such as supply and demand, economic conditions, and political events. As a knowledgeable professor, it is important to understand the implications of steep declines in market prices and their potential impact on financial markets.