You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Yale_University

Context:
Yale is organized into fourteen constituent schools: the original undergraduate college, the Yale Graduate School of Arts and Sciences, and twelve professional schools. While the university is governed by the Yale Corporation, each school's faculty oversees its curriculum and degree programs. In addition to a central campus in downtown New Haven, the University owns athletic facilities in western New Haven, including the Yale Bowl, a campus in West Haven, Connecticut, and forest and nature preserves throughout New England. The university's assets include an endowment valued at $25.6 billion as of September 2015, the second largest of any educational institution.The Yale University Library, serving all constituent schools, holds more than 15 million volumes and is the third-largest academic library in the United States.

Question:
How much is Yale's endowment worth?

$25.6 billion