Bill and Melinda Gates, who run the largest philanthropy in the world, published their annual letter this morning, and it exudes the optimism that Bill expressed when he guest-edited TIME magazine last month. In the letter, the two also make a good faith effort to answer what they say are the 10 toughest questions they get asked about their philanthropy.

One that caught my attention was this: Why do you work with corporations?

Is that a “tough question”? This gets back to the New York Times column I cited yesterday, which disparaged business efforts to address what have traditionally been public sector issues—like fixing the health care system, exploring space, or providing general education and training.

I talked with Melinda a few days ago, and she provided some insight.

“Bill and I think the private sector is vital in the equation” of addressing social problems. “We always try to have in the back of our mind: What’s the role of government, NGOs, philanthropy, the private sector?”

The private sector, she says, is growing in importance. “Things are shifting. Perceptions are shifting. Companies are being pushed by their millennial workforce, which is asking them to do these things… It’s not just CSR anymore. Companies want to do the right thing for their employees and their customers.”

In their letter, the Gates mentioned working with GSK, Johnson & Johnson and Monsanto on various initiatives. In our conversation, Melinda cited work the foundation is doing with Merck and Bayer on reproductive health. “We have more and more companies approaching us, and approaching us with good ideas.”

Is there a limit to the private sector’s ability to address such problems? Of course. “They aren’t very good at reaching the bottom billion,” Melinda says. But that still leaves plenty of scope for constructive action.

More news below—including the President’s new infrastructure plan, which would put much more of that responsibility into private sector hands.

Top News

Trump Budget Proposal

The White House yesterday proposed a budget that would remove billions of dollars from food stamps, federal housing and public health insurance programs that are designed to help poorer Americans. Libertarian groups were delighted at the proposal, which would replace food stamps with a boxed food delivery program that White House budget director Mick Mulvaney compared to Blue Apron. Fortune

Zuma Almost Out

South Africa's ruling party, the African National Congress, has recalled President Jacob Zuma, but has not given him a deadline to respond to the order. Dogged by hundreds of corruption allegations, Zuma has been determined to avoid handing over power to new ANC president Cyril Ramaphosa for as long as possible. Ramaphosa, currently the country's deputy president, is a veteran of the struggle against Apartheid who went on to become an extremely wealthy businessman before returning to politics. Times Live

Point72 Asset Management Suit

Hedge fund manager Steven Cohen's firm has been sued by a female employee who alleged unfair pay practices and a sexist working environment. Recruiter Lauren Bonner said she was paid up to two-thirds less than her male counterparts, and claimed that a Point72 executive said there were "no girls allowed" in some meetings. Wall Street Journal

Hooray for Protectionism?

A GE survey of executives found that more than half are in favor of protectionism as a way of increasing competitiveness in their sectors. Of that 55%, almost three quarters said workers would benefit and 60% said it would "foster ideas" on their home turf. "Global executives want the best of both worlds: on one hand they want the benefits of protectionist policies on domestic businesses and jobs, and on the other hand, they want the benefits of globalization and open markets," GE's report noted. GE

Around the Water Cooler

Trump's Infrastructure Promise

What will come of Trump's promise to turn a $200 billion federal government investment into $1.5 trillion in infrastructure spending, with the rest coming from the private sector? Not much, according to Lindsay Koshgarian of the Institute for Policy Studies, who writes for Fortune that "just like Mexico won’t pay for a border wall, private investors won’t pay for roads, bridges, and energy infrastructure just because the president says they will." Fortune

Zuckerberg's Trials

Wired has a blockbuster cover story on Mark Zuckerberg's last two years, which have been rather testing for the Facebook CEO. Based on dozens of interviews with insiders, the story covers Zuckerberg's slow, reluctant shift in attitude regarding the platform's status as a publisher—something Facebook refused to acknowledge until things started to go terribly wrong. Wired

Bitcoin Volatility

Bitcoin investors, not exchanges, are responsible for the terrific volatility in the cryptocurrency market—according to the CEO of an exchange. Kraken chief Jesse Powell said his exchange did its utmost to ensure that the cryptocurrencies it deals with are "almost certainly not a scam," but ultimately "we make no promises about the future of any coin." CNBC

AI vs. IS

The British government has co-developed an "artificial intelligence" program that it says can detect online Islamic State propaganda with a 94% success rate. The Home Office said the software could stop most of the terrorist organization's videos from reaching people's eyeballs automatically, with only a small proportion requiring human review before their blocking. Guardian

This edition of CEO Daily was edited by David Meyer. Find previous editions here, and sign up for other Fortune newsletters here.