U.S. government steps up an investigation into Chipotle's hiring practices; in 2010, company fired about 450 employees who could not prove they were eligible to work in the U.S.

NEW YORK , May 4, 2011 () – Shares of Chipotle Mexican Grill Inc. slipped in early trading Wednesday after the U.S. government stepped up an investigation into the chain's hiring practices.

THE SPARK: Confirming earlier media reports, the company said U.S. Immigration and Customs officials visited about 25 Chipotle locations around the country, and interviewed managers and supervisors. Chipotle said the visits were spread out across a handful of cities.

THE BIG PICTURE: Chipotle has faced scrutiny over its hiring in the past. In April, the Denver fast food chain disclosed that federal prosecutors were investigating issues related to employee documentation. In 2010, the company fired about 450 employees who could not prove they were eligible to work in the U.S.

The company employs about 26,500 workers, according to FactSet.

SHARE ACTION: Chipotle stock declined as much as 4.2 percent on Wednesday. In afternoon trading, the stock slid 71 cents to $259.70. Chipotle shares have doubled in value over the last year and traded as high as $289.35 in April.

© 2019 Associated Press. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.