Facebook FB +4.11% CEO Mark Zuckerberg sold another $95 million in Facebook stock within the past week, another step towards his goal of donating 99% of his Facebook stake to improve the world within his lifetime.The Chan Zuckerberg Foundation and CZI Holdings LLC, the two entities that Zuckerberg and his wife Priscilla Chan created for their philanthropy and public advocacy last year, sold the shares between Nov. 17 and Nov. 18, according to regulatory filings. The sale follows $190 million in Facebook stock sold by the same entities in October and another $190 million sold in September. Zuckerberg says he will not sell or give away more than $1 billion in Facebook stock per year through 2018, according to the filing.Chan and Zuckerberg announced one big goal in September, when they pledged to spend $3 billion over the next decade to fight disease. “If we can develop new tools, we can empower scientists all around the world to make much faster progress and breakthroughs,” Zuckerberg said at the time.