Definition of 'Stub Quote'
Order placed well off a stock's market price. Stub quotes are used by trading firms when the firm doesn't want to trade at certain prices and wants to pull away to ensure no trades occur. In order to make this happen, the firm will offer quotes that are out of bounds. A stub quote also serves as a safety net in that if a market maker doesn't have enough liquidity available to trade a stock near its recent price range, then a stub quote is entered so that the market maker complies with its requirements without extending its quotes beyond its available liquidity.
A stub quote is also referred to as a "placeholder" quote because this absurdly priced transaction would never be reached.
Investopedia explains 'Stub Quote'
For example, a trading firm might set stub bids at 1 cent and stub offers at $2,000. Since the quotes are so dramatic, on a normal market trading day, these types of trades are generally not executed.
Stub quotes are blamed as one of the causes of the 2010 May "Flash Crash" when the Dow Jones Industrial Average dropped nearly 1,000 points because the "out of bounds" prices that the stub quotes are known for were inadvertently executed when the market dropped dramatically that day.