TD didn't commit to $20B their letter only says they're "highly confident" they could raise that much. Very important distinction between the two.
The letter also said it was conditional on the combined entity maintaining investment-grade credit rating, which seems unlikely if the combined entity was saddled with $20B in debt.
The letter also said it was conditional on the combined entity maintaining investment-grade credit rating, which seems unlikely if the combined entity was saddled with $20B in debt.