Stanford University announced Tuesday that it would divest its $18.7 billion endowment of stock in coal-mining companies, becoming the first major university to lend support to a nationwide campaign to purge endowments and pension funds of fossil fuel investments.

The university said it acted in accordance with internal guidelines that allow its trustees to consider whether “corporate policies or practices create substantial social injury” when choosing investments. Coal’s status as a major source of carbon pollution linked to climate change persuaded the trustees to remove companies “whose principal business is coal” from their investment portfolio, the university said.

Stanford’s associate vice president for communications, Lisa Lapin, said the decision covers about 100 companies worldwide that derive the majority of their revenue from coal extraction. Not all of those companies are in the university’s investment portfolio, whose structure is private, she said. Over all, the university’s coal holdings are a small fraction of its endowment.

“But a small percentage is still a substantial amount of money,” she added.

The trustees’ decision carries more symbolic than financial weight, but it is a major victory for a rapidly growing student-led divestment movement that is now active at roughly 300 universities.