SAN FRANCISCO — Mark Zuckerberg, chief executive officer of Facebook Inc., has donated 18 million Facebook shares, valued at $498.8 million, to a Silicon Valley charity that works with donors to allocate gifts to health and education causes.
The gift is Mr. Zuckerberg's largest to date. He pledged $100 million in Facebook stock to Newark, N.J., public schools in 2010, before his company went public this year.