<ACCESSION-NUMBER>0001031296-18-000015 <TYPE>10-K <PUBLIC-DOCUMENT-COUNT>164 <PERIOD>20171231 <FILING-DATE>20180220 <DATE-OF-FILING-DATE-CHANGE>20180220 <FILER> <COMPANY-DATA> <CONFORMED-NAME>FIRSTENERGY CORP <CIK>0001031296 <ASSIGNED-SIC>4911 <IRS-NUMBER>341843785 <STATE-OF-INCORPORATION>OH <FISCAL-YEAR-END>1231 </COMPANY-DATA> <FILING-VALUES> <FORM-TYPE>10-K <ACT>34 <FILE-NUMBER>333-21011 <FILM-NUMBER>18625430 </FILING-VALUES> <BUSINESS-ADDRESS> <STREET1>76 SOUTH MAIN ST <CITY>AKRON <STATE>OH <ZIP>44308-1890 <PHONE>330-761-7837 </BUSINESS-ADDRESS> <MAIL-ADDRESS> <STREET1>76 SOUTH MAIN ST <CITY>AKRON <STATE>OH <ZIP>44308-1890 </MAIL-ADDRESS> </FILER> <FILER> <COMPANY-DATA> <CONFORMED-NAME>FirstEnergy Solutions Corp. <CIK>0001407703 <ASSIGNED-SIC>4911 <IRS-NUMBER>311560186 <STATE-OF-INCORPORATION>OH <FISCAL-YEAR-END>1231 </COMPANY-DATA> <FILING-VALUES> <FORM-TYPE>10-K <ACT>34 <FILE-NUMBER>000-53742 <FILM-NUMBER>18625431 </FILING-VALUES> <BUSINESS-ADDRESS> <STREET1>C/O FIRSTENERGY CORP. <STREET2>76 SOUTH MAIN STREET <CITY>AKRON <STATE>OH <ZIP>44308 <PHONE>800-736-3402 </BUSINESS-ADDRESS> <MAIL-ADDRESS> <STREET1>C/O FIRSTENERGY CORP. <STREET2>76 SOUTH MAIN STREET <CITY>AKRON <STATE>OH <ZIP>44308 </MAIL-ADDRESS> </FILER>