M&S is a supermarket chain with a revenue of £10 billion, 70’000+ employees and a 135 year history. I spent the first 6 months of my professionals life in M&S and as far as I could guesstimate from the information I had access to, M&S has raised roughly £50 million per year for charity for the past decade. In a shockingly unsurprising twist, most of this money went to highly ineffective charities. I doubt M&S is exceptional in this regard.
Like M&S, most large corporations have CSR schemes which raise significant amounts of money. Like M&S, most direct the money raised to popular, well known charities without much regard for effectiveness. This is a waste and, I think, an opportunity. An NGO aimed at persuading blue chips to fund effective charities would not be a bad way for some practically minded effective altruists to do a great deal of good.