Ultra Petroleum Corp. (NYSE: UPL), a major victim of depressed oil and gas prices, filed for Chapter 11 bankruptcy on April 29 in Houston.

The Texas-based company, which has operations in Wyoming's Pinedale Field, Utah's Uinta Basin and Pennsylvania's Marcellus Shale, listed assets in the range of $1 billion to $10 billion, and liabilities of $1 billion to $10 billion, according to a court filing.

The company's bankruptcy shows the stress the oil and gas industry is under as oil prices stay below $50 per barrel, down from above $100 almost two years ago.

Ultra's total debt stood at about $3.9 billion as of March 31, according to its quarterly filing. The company had 167 employees as of Dec. 31.

Ultra may have to seek protection from its creditors in bankruptcy, the company said in its quarterly report filed with the U.S. Securities and Exchange Commission.

The company entered into a waiver period extending until April 30 more than $100 million in payments that were due March 1.

Ultra also deferred making a $26 million interest payment due April 1, beginning a 30 day-grace period.

Up to a third of all oil producers may end up in bankruptcy this year if commodity prices remain depressed, according to consulting firm Deloitte.

The case is in U.S. Bankruptcy Court, Southern District of Texas (Houston), Case No: 16-32202.