The steady and sharp fall in coal prices has knocked down shares of big mining companies like BHP Billiton (NYSE: BBL - news ) , Glencore (Xetra: A1JAGV - news ) and Rio Tinto (LSE: RIO.L - news ) , and it has seen many financers exit the sector.
Analyze the relationship between 'Glencore' and 'mining' within the context of the input sentence.
Options: stock exchange, chairperson, product/material produced, industry