We analyze the effect of business and financial market cycles on credit ratings using a sample of firms from the Russell 3000 index that are rated by Standard and Poor's over the period 1986–2012. We also examine investor reaction to credit rating actions in different stages of business and financial market cycles. We document that credit rating agencies are influenced by business and financial market cycles; they assign lower credit ratings during downturns of business and financial market cycles and higher ratings during upturns. Our study is the first to find strong evidence of pro‐cyclicality in credit ratings using a long window. We also document stronger investor reaction to negative credit rating actions during downturns. Our results confirm theoretical predictions and inform regulators.