Casino owner Penn Entertainment's PENN.O shares jumped 18.8% in premarket trading on a $2 billion deal with Walt Disney's ESPN DIS.N to launch a sports betting business. Walt Disney's shares rose 1.4% ahead of its quarterly results due after markets close. By Bansari Mayur Kamdar and Johann M Cherian Aug 9 (Reuters) - Wall Street was set to open higher on Wednesday following a risk-off session triggered by a Moody's downgrade of some banks, with investors looking ahead to a key inflation report this week after mostly dovish comments from Federal Reserve officials.