NEW YORK (AP) - The largest American coal miner, Peabody Energy, is delaying an interest payment due this week and warned that it may have to file for Chapter 11 bankruptcy protection.

NEW YORK (AP) The largest American coal miner, Peabody Energy, is delaying an interest payment due this week and warned that it may have to file for Chapter 11 bankruptcy protection.

Shares of Peabody Energy Corp. plummeted nearly 40 percent before the market opened Wednesday.

A slowing global economy and toughening environmental standards have slammed the coal industry, which is already beset by bankruptcies, shuttered mines and layoffs.

Rivals Patriot Coal and Arch Coal have already filed for bankruptcy protection in the last year.

The St. Louis miner says it didn't pay more than $70 million in interest payments that were due Tuesday. If the company doesn't make the payment in 30 days, it would default and its says there's "substantial doubt" it would be able to go on.