Casino and racetrack operator Penn National Gaming said on Thursday its $6.1 billion takeover pact has been terminated, marking the latest leveraged buyout to crumble amid the tight credit markets and weak U.S. economy.

United Rentals Inc. said Tuesday that it will waive a condition to the equipment rental company's ongoing tender offer that its stock cannot fall more than 10 percent below the June 16 closing price.

Alliance Data Systems said Friday it terminated a $6.76 billion sale to Blackstone Group affiliates and has sued to win a $170 million business interruption payment.

Equipment rental group United Rentals said it terminated its $4 billion takeover by Cerberus Capital Management and asked Cerberus to pay it a $100 million termination fee.