Carl Icahn is having a terrible day

Monday's ugly open is turning into an especially horrible experience for billionaire investor Carl Icahn.

Icahn holds 73 million shares of Chesapeake Energy, which fell more than 50% on a news report that it has hired a team of lawyers to restructure its debt.

The stock has been halted is now down 64% year to date.

Icahn started buying commodities/energy stocks like Chesapeake in earnest last summer, growing his stake in Cheniere, and buying an 8.5% stake miner Freeport-McMoRan.

As Business Insider's Portia Crowe pointed out last month, that hasn't worked out so well for him in general. Take those two stocks alone as an example:

• Cheniere fell 6.25% in Monday's trading, and is down 35% year to date.
• Freeport-McMoRan is up 1.23% in Monday's trading, but is down 14% for the year.

As of September 2015, energy stocks were the third largest sector holding in Icahn's portfolio.