Exhibit 99 Form 4 Joint Filer Information Name: EnCap Energy Capital Fund VIII Co-Investors, L.P. Address: 1100 LOUISIANA STREET, SUITE 4900 HOUSTON, TX 77002 Issuer & Ticket Symbol: Eclipse Resources Corporation [ECR] Date of Event Requiring Statement: 12/27/2014 Relationship of Reporting Person to Issuer: 10% Owner Signature: EnCap Energy Capital Fund VIII Co-Investors, L.P. By: EnCap Equity Fund VIII GP, L.P., its general partner By: EnCap Investments L.P., its general partner By: EnCap Investments GP, L.L.C, its general partner By: /s/ D. Martin Phillips, Sr. Managing Director --------------------------------------------- Date: 12/30/2014 Name: EnCap Energy Capital Fund IX, L.P. Address: 1100 LOUISIANA STREET, SUITE 4900 HOUSTON, TX 77002 Issuer & Ticket Symbol: Eclipse Resources Corporation [ECR] Date of Event Requiring 12/27/2014 Statement: Relationship of Reporting Person to Issuer: 10% Owner Signature: EnCap Energy Capital Fund IX, L.P. By: EnCap Equity Fund IX GP, L.P., its general partner By: EnCap Investments L.P., its general partner By: EnCap Investments GP, L.L.C, its general partner By: /s/ D. Martin Phillips, Sr. Managing Director --------------------------------------------- Date: 12/30/2014 Name: EnCap Investments GP, L.L.C. Address: 1100 LOUISIANA STREET, SUITE 4900 HOUSTON, TX 77002 Issuer & Ticket Symbol: Eclipse Resources Corporation [ECR] Date of Event Requiring Statement: 12/27/2014 Relationship of Reporting Person to Issuer: 10% Owner Signature: EnCap Investments GP, L.L.C. By: /s/ D. Martin Phillips, Sr. Managing Director --------------------------------------------- Date: 12/30/2014 Name: RNBD GP LLC Address: 1100 LOUISIANA STREET, SUITE 4900 HOUSTON, TX 77002 Issuer & Ticket Symbol: Eclipse Resources Corporation [ECR] Date of Event Requiring Statement: 12/27/2014 Relationship of Reporting Person to Issuer: 10% Owner Signature: RNBD GP LLC By: /s/ D. Martin Phillips, Member --------------------------------------------- Date: 12/30/2014 Name: Gary R. Petersen Address: 1100 LOUISIANA STREET, SUITE 4900 HOUSTON, TX 77002 Issuer & Ticket Symbol: Eclipse Resources Corporation [ECR] Date of Event Requiring Statement: 12/27/2014 Relationship of Reporting Person to Issuer: 10% Owner Signature: /s/ Gary R. Petersen ------------------------------------------------ Date: 12/30/2014 Name: David B. Miller Address: 1100 LOUISIANA STREET, SUITE 4900 HOUSTON, TX 77002 Issuer & Ticket Symbol: Eclipse Resources Corporation [ECR] Date of Event Requiring Statement: 12/27/2014 Relationship of Reporting Person to Issuer: 10% Owner Signature: /s/ David B. Miller ------------------------------------------------- Date: 12/30/2014 Name: Robert L. Zorich Address: 1100 LOUISIANA STREET, SUITE 4900 HOUSTON, TX 77002 Issuer & Ticket Symbol: Eclipse Resources Corporation [ECR] Date of Event Requiring Statement: 12/27/2014 Relationship of Reporting Person to Issuer: 10% Owner and Director Signature: /s/ Robert L. Zorich ------------------------------------------------ Date: 12/30/2014 Name: D. Martin Phillips Address: 1100 LOUISIANA STREET, SUITE 4900 HOUSTON, TX 77002 Issuer & Ticket Symbol: Eclipse Resources Corporation [ECR] Date of Event Requiring Statement: 12/27/2014 Relationship of Reporting Person to Issuer: 10% Owner and Director Signature: /s/ D. Martin Phillips ------------------------------------------------ Date: 12/30/2014