PIMCO Corporate & Income Opportunity Fund is a closed-ended mutual fund focusing on fixed income investments globally. Managed by Allianz Global Investors and co-managed by Pacific Investment Management Company, it primarily invests in corporate debt rated at the lower end of investment grade or the higher end of non-investment grade. The fund, founded in 2002 and based in the United States, targets intermediate maturity bonds across various industries, using fundamental analysis and a top-down approach, backed by in-house research.