Philip Halpern will leave the $3.5 billion University of Chicago endowment, where he is vice president and CIO, effective June 30. He decided to step down after six years in the position because of a difference in philosophies with the investment committee, he said. Mr. Halpern said he is considering other CIO positions, entrepreneurial endeavors or working full time on a book project. "I prefer to stay in Chicago, if possible," he said. Don Michael Randel, university president, said in an internal memo that the university expects to begin a search for a replacement soon. His memo also said that Mr. Halpern's "accomplishments…are numerous. Performance against the strategic policy and against other universities with similar-sized endowments has been strong. He has recruited a superb staff … his reputation in the industry is outstanding," Fund officials couldn't be reached for comment.