Flaherty & Crumrine Preferred Income Opportunity Fund Inc. is a closed ended equity mutual fund launched and managed by Flaherty & Crumrine Incorporated. The fund invests in the public equity markets of the United States. It invests in stocks of companies operating in the financial services sector. The fund primarily invests in preferred securities. It benchmarks the performance of its portfolio against S&P 500 Index and Barclays Capital U.S. Aggregate Index. Flaherty & Crumrine Preferred Income Opportunity Fund Inc. was formed on December 10, 1991 and is domiciled in the United States.