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( Mark One ) UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON , D.C. 20549 □ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31 , 2020 or Commission File Number □ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 FORM 10 - K For the transition period from Registrants ; Address and Telephone Number AMERICAN ELECTRIC POWER CO INC . 1-3525 333-221643 AEP TEXAS INC . 333-217143 AEP TRANSMISSION COMPANY , LLC 1-3457 APPALACHIAN POWER COMPANY 1-3570 INDIANA MICHIGAN POWER COMPANY 1-6543 OHIO POWER COMPANY 0-343 PUBLIC SERVICE COMPANY OF OKLAHOMA SOUTHWESTERN ELECTRIC POWER COMPANY 1-3146 1 Riverside Plaza , Columbus , Ohio 43215-2373 Telephone ( 614 ) 716-1000 Securities registered pursuant to Section 12 ( b ) of the Act : Title of each class Common Stock , $ 6.50 par value 6.125 % Corporate Units 6.125 % Corporate Units Registrant American Electric Power Company Inc. American Electric Power Company Inc. American Electric Power Company Inc. to States of Incorporation AEP AEPPL AEPPZ New York Delaware Delaware Virginia Indiana Ohio Oklahoma Delaware I.R.S. Employer Identification Nos . 13-4922640 51-0007707 46-1125168 54-0124790 35-0410455 31-4271000 73-0410895 72-0323455 Trading Symbol Name of Each Exchange on Which Registered The NASDAQ Stock Market LLC The NASDAQ Stock Market LLC The NASDAQ Stock Market LLC