A rule set by the New York Stock Exchange to determine a minimum market value to be listed continuously. The Market Capitalization Rule states that companies must maintain a minimum value of $25 million over 30 consecutive days to remain listed. This standard value was set in 2004.
Taobiz explains Market Capitalization Rule
Due to the downturn of the global economy in 2008-2009, the NYSE temporarily amended the market capitalization rule in January of 2009. The minimum value was reduced so that companies who are able to maintain a market value of over $15 million for 30 trading days in a row would remain listed until April 22, 2009.