Christopher Browne, a genteel money manager who helped bring down newspaper baron Conrad Black, died Sunday of a heart attack.

Mr. Browne appears to have been 63, although his firm, Tweedy Browne & Co., couldn't immediately confirm that.

Although relatively small with about $10 billion in assets under management, Tweedy Browne is known for its ability to sniff out bargains most investors missed. Mr. Browne succinctly spelled out the firm's buy-on-the-cheap strategy in his 2006 tome titled The Little Book of Value Investing.

“Buy stocks like when you buy everything else,” he advised readers, “when they are on sale.” He frequently likened the value investing strategy to “buying $1 for 66 cents.”

Mr. Browne was a trustee of the Paley Center for Media and Rockefeller University, home of the Christopher H. Browne Center for Immunology and Immune Diseases. He also was a longtime trustee of the University of Pennsylvania, establishing a center for international politics at the school's political science department and leading the effort to build the Penn Club of New York on West 44th Street.

He stepped down from Tweedy Browne's management and investment committees in July, citing health reasons. “I took this as a wakeup call about the fragility of life,” Mr. Browne said, in a statement at the time.