PIMCO Corporate & Income Opportunity Fund (the Fund) is a diversified, closed-end management investment company. The objective of the Fund is to seek high current income with capital preservation and capital appreciation as secondary objectives. Generally, 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 U.S. Government securities, municipal securities, and mortgage-backed and other asset-backed securities issued on a public or private basis. The fund will normally invest at least 25% of its total assets in corporate debt obligations and other corporate income-producing securities. The Fund's investment manager is Allianz Global Investors Fund Management LLC and its sub-advisor is Pacific Investment Management Company LLC.