0000891836-12-000058 SC 13D/A 2 20120523 20120523 EDWARD H. MCDERMOTT J. STUART RYAN JOHN H. SCULLY PHOEBE SNOW FOUNDATION INC. SF ADVISORY PARTNERS L.P. SPO ADVISORY PARTNERS L.P. SPO FRANCISCO PARTNERS L.P. SPO PARTNERS II CO-INVESTMENT PARTNERSHIP L.P. SPO PARTNERS II L.P. CALPINE CORP 0000916457 4911 770212977 DE 1231 SC 13D/A 34 005-48317 12864953 717 TEXAS AVENUE SUITE 1000 HOUSTON TX 77002 7138302000 717 TEXAS AVENUE SUITE 1000 HOUSTON TX 77002 SPO ADVISORY CORP 0000919468 680247274 DE 1231 SC 13D/A 591 REDWOOD HIGHWAY SUITE 3215 MILL VALLEY CA 94941 4153836600 591 REDWOOD HIGHWAY SUITE 3215 MILL VALLEY CA 94941 SF ADVISORY CORP 19990329 SC 13D/A 1 sc0037-12.htm AMENDMENT NO. 9 TO SCHEDULE 13D EX-99.A 2 ex_99-a.htm AGREEMENT PURSUANT TO RULE 13D-1(K)