0000916457-17-000068 4 1 20170510 20170512 20170512 CALPINE CORP 0000916457 4911 770212977 DE 1231 717 TEXAS AVENUE SUITE 1000 HOUSTON TX 77002 7138302000 717 TEXAS AVENUE SUITE 1000 HOUSTON TX 77002 BRLAS LAURIE 0001235612 4 34 001-12079 17838781 C/O CLIFFS NATURAL RESOURCES INC. 200 PUBLIC SQUARE, SUITE 3300 CLEVELAND OH 44114 4 1 wf-form4_149461999656106.xml FORM 4