Investors were bailing out on Equifax a day after the credit monitoring company said a data breach exposed the Social Security numbers and other personal data of 143 million Americans.
Equifax shares fell about 13 percent to $123.75 in heavy trading. The decline equates to about $2.28 billion in lost market value.
The company is one of three major U.S. credit bureaus, the declines extended to its competitors. TransUnion fell 4 percent and Experian stock declined 1 percent in London.
Lenders rely on the information collected by the credit bureaus to help them decide whether to approve financing for homes, cars and credit cards. Credit checks are even sometimes done by employers when deciding whom to hire for a job.