PIMCO Corporate & Income Opportunity Fund (the Fund), formerly PIMCO Corporate Opportunity Fund, is a closed-end exchange traded investment company. The Fund seeks total return through a combination of current income and capital appreciation. The Fund invests at least 80% of its total assets in a combination of corporate debt obligations of varying maturities, other corporate income-producing securities, and income-producing securities of non-corporate issuers, such as the United States Government securities, municipal securities and mortgage-backed and other asset-backed securities issued on a public or private basis. Allianz Global Investors Fund Management LLC serves as the Funds' investment manager, and the sub-advisors are Pacific Investment Management Company LLC (PIMCO), Allianz Global Investors Capital (AGIC), and NFJ Investment Group LLC. (NFJ).