X0306 4/A 2015-01-30 2015-02-03 1 0001190935 PIMCO CORPORATE & INCOME OPPORTUNITY FUND PTY 0001201891 GROSS WILLIAM H 151 DETROIT STREET DENVER CO 80206 0 0 0 1 SEE REMARKS COMMON STOCK 2015-01-30 4 S 0 50000 16.6304 D 1085671 D COMMON STOCK 708611 I BY CHILD TRUST #1 COMMON STOCK 694668 I BY CHILD TRUST #4 COMMON STOCK 724874 I BY CHILD TRUST #7 COMMON STOCK 13400 I BY CHILD TRUST #8 COMMON STOCK 10762 I BY CHILD TRUST #10 COMMON STOCK 10762 I BY CHILD TRUST #11 COMMON STOCK 10763 I BY CHILD TRUST #12 The price reported in Column 4 is a weighted average price. These shares were disposed of in multiple transactions at prices ranging from $16.61 to $16.71, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares disposed of at each separate price within the ranges set forth in this footnote. The Reporting Person is a former Portfolio Manager of the Issuer. The Reporting Person ceased being affiliated with the Issuer effective September 27, 2014. /s/ Amy J. Stefonick, Attorney-in-Fact for William H. Gross 2015-02-18