Tallgrass Energy SC 13E3/A Going private transaction (amended)

Exhibit (c)27

Preliminary and Confidential – Subject to Further Review and Revision Citigroup Global Markets Inc. | Global Energy Group June 2019 Project Prairie 2.0 Discussion Materials Strictly Private and Confidential

Preliminary and Confidential – Subject to Further Review and Revision Relative Historical Trading Performance Price Performance – LTM 15.00% Price Performance Since Closing (%) 5.00% (0.85%) (2.06%) (5.00%) (8.42%) 30.00% (15.00%) 3/11/2019 3/26/2019 4/11/2019 4/27/2019 5/13/2019 5/29/2019 6/14/2019 20.00% 10.00% 3.00% 0.00% (1.67%) (8.19%) (10.00%) (20.00%) (30.00%) 6/14/2018 7/29/2018 9/13/2018 10/28/2018 12/13/2018 1/28/2019 3/14/2019 4/29/2019 6/14/2019 % Implied Premium / (Discount) 15.00% Price Performance Since Announcement Price Price $23.00 $24.00 $25.00 $26.00 At Announcement $24.18 (4.9%) (0.7%) 3.4% 7.5% 5.00% At Closing 23.76 (3.2) 1.0 5.2 9.4 2.02% Current 21.76 5.7 10.3 14.9 19.5 (2.12%)10-Day VWAP 22.76 1.1 5.5 9.9 14.3 (5.00%)30-Day VWAP 23.52 (2.2) 2.0 6.3 10.5 (10.01%)60-Day VWAP 24.03 (4.3) (0.1) 4.0 8.290-Day VWAP 23.82 (3.4) 0.8 5.0 9.2 (15.00%)52-Week High 26.35 (12.7) (8.9) (5.1) (1.3) 1/30/2019 2/21/2019 3/16/2019 4/7/2019 4/30/2019 5/22/2019 6/14/201952-Week Low 20.36 13.0 17.9 22.8 27.7 Source: FactSet. Market data as of 6/14/2019. Peer Set(1) Thunder AMZ (1) Thunder peers include ENB, EPD, ET, KMI, TRP, WMB, MMP, OKE, DCP, MPLX, TRGP and PAA. 1

Preliminary and Confidential – Subject to Further Review and Revision Analyst Price Targets Pre and Post Deal Announcement Analysts Price Targets and RatingsPre-Announcement Post-Announcement % Change Current % Change Broker Date Rating Price Target Date Rating Price Target Since Ann. Date Rating Price Target Since Ann. Capital One Securities, Inc. 01/30/19 Hold $27.00 02/15/19 Hold $27.00 0.0% 05/08/19 Hold $28.00 3.7% Tudor Pickering & Co 01/29/19 Hold 24.00 02/12/19 Hold 24.00 0.0 04/23/19 Hold 24.00 0.0 Baird 01/28/19 Buy 28.00 01/31/19 Buy 28.00 0.0 04/25/19 Buy 28.00 0.0 US Capital Advisors 01/28/19 Hold 23.00 02/06/19 Hold 23.00 0.0 05/24/19 Hold 24.00 4.3 Barclays 01/16/19 Hold 26.00 01/31/19 Hold 26.00 0.0 05/08/19 Hold 26.00 0.0 Credit Suisse 01/15/19 Buy 26.00 01/31/19 Buy 26.00 0.0 06/11/19 Hold 25.00 (3.8) Stifel 12/21/18 Buy 25.00 02/04/19 Buy 26.00 4.0 06/13/19 Buy 26.00 0.0 Wells Fargo Securities 12/04/18 Hold 26.00 02/06/19 Hold 25.00 (3.8) 06/05/19 Hold 25.00 0.0 RBC Capital Markets 12/02/18 Hold 25.00 02/05/19 Hold 24.00 (4.0) 05/08/19 Hold 24.00 0.0 MUFG Securities Americas, Inc 11/01/18 Hold 26.00 01/31/19 Hold 26.00 0.0 05/07/19 Hold 27.00 3.8 Goldman Sachs 10/08/18 Buy 27.00 02/12/19 Buy 26.00 (3.7) 04/02/19 Hold 26.00 0.0 Median $26.00 $26.00 0.0% $26.00 0.0% Recommendation History 100% $30.00 17% 17% 25% 23% 31% 33% 31% 31% $25.00 80% 40% 40% 40% 40% 38% $20.00 60% $15.00 75% 75% 40% 67% 69% 62% 58% 62% 69% 53% 54% $10.00 60% 60% 60% 20% $5.00 8% 8% 8% 7% 8% 8% 8% 8% 8% 0% $0.00 6/18 7/18 8/18 9/18 10/18 11/18 12/18 1/19 2/19 3/19 4/19 5/19 6/19 6/15/2018 7/15/2018 8/15/2018 9/15/2018 % 10/15/2018 Sell %11/15/2018 Hold 12/15/2018 % Buy 1/15/2019 Actual 2/15/2019 Target Unit Price 3/15/2019 4/15/2019 5/15/2019 Source: Bison projections, Public filings, FactSet, and Wall Street research. Market data as of 6/14/2019. 2 Note: “N/A” denotes not publicly available.

Preliminary and Confidential – Subject to Further Review and Revision Selected Public Companies Analysis Diversified Peers Closing Firm Value / ($ in Millions, Except Per Unit Data) Unit Price Equity Value ($mm) Firm EBITDA (x) Yield‘19-‘21 DCF‘19-‘21 Dist. Price / DCF Coverage Debt / Name 6/14/2019 LP Units Total Value 2019E 2020E Indicative(1) 2019E 2020E CAGR (%) CAGR (%) 2019E 2020E 2019E 2020E 2018E EBITDA Enbridge Inc. $34.48 $69,844 $69,911 $125,531 12.7x 12.1x 6.4% 6.4% 7.1% 8.2% 8.0% 10.5x 9.9x 1.49x 1.44x 5.0x Enterprise Products Partners LP 29.07 64,019 64,019 91,260 11.7 11.3 6.0 6.1 6.3 1.9 3.6 10.4 10.4 1.57 1.53 3.4 TC Energy Corporation 48.94 45,367 45,484 87,008 12.6 12.2 4.6 4.6 5.0 6.3 8.8 9.3 8.9 2.34 2.26 5.5 Energy Transfer, LP 14.17 37,438 37,438 85,953 8.0 8.0 8.6 8.6 8.6 1.3 2.8 6.2 6.4 1.87 1.83 4.2 Kinder Morgan Inc. 20.53 46,475 46,475 83,633 10.9 10.4 4.9 4.9 6.1 6.6 14.5 9.4 8.7 2.18 1.90 4.7 Williams Companies 26.99 32,755 32,755 55,246 10.9 10.6 5.6 5.6 6.3 6.0 12.1 10.6 10.2 1.68 1.54 4.2 (4) MPLX LP 31.25 33,146 33,146 53,133 10.1 9.3 8.4 8.6 9.1 3.7 2.9 8.1 7.5 1.44 1.46 3.5 ONEOK, Inc. 64.46 26,753 26,753 37,037 14.1 11.7 5.4 5.6 6.1 13.4 9.1 13.3 11.5 1.34 1.42 3.9 Plains All American Pipeline LP 24.11 17,688 17,688 28,870 10.1 10.2 6.0 6.0 6.3 (1.2) 5.1 8.9 9.3 1.89 1.72 3.3 Targa Resources Corp. 36.59 8,683 8,683 18,541 14.1 11.0 9.9 9.9 9.9 22.4 1.4 11.7 9.2 0.86 1.10 4.6 DCP Midstream Partners 28.78 4,125 5,703 11,858 9.6 8.6 10.8 10.8 11.0 3.7 2.1 7.8 7.3 1.27 1.36 4.8 High $125,531 14.1x 12.2x 10.8% 10.8% 11.0% 22.4% 14.5% 13.3x 11.5x 2.34x 2.26x 5.5x Median 55,246 10.9 10.6 6.0 6.1 6.3 6.0 5.1 9.4 9.2 1.57 1.53 4.2 Mean 61,643 11.3 10.5 7.0 7.0 7.4 6.6 6.4 9.7 9.0 1.63 1.60 4.3 Low 11,858 8.0 8.0 4.6 4.6 5.0 (1.2) 1.4 6.2 6.4 0.86 1.10 3.3 Thunder $21.76 $6,199 $6,199 $9,925 10.2x 10.1x 9.1% 9.6% 10.1% 2.9% 5.0% 8.0x 8.2x 1.30x 1.21x 4.6x (5) Selected Reference Range(2) Implied Equity Selected Range Implied Firm Value(3) Implied Equity Value(3) Value per Share(3) ($ in millions, except per unit figures) Metric Low High Low High Low High Low High FV / EBITDA 2019E $973 9.6x 10.9x $9,323 $10,630 $6,007 $7,313 $21.22 $25.83 2020E 979 8.6 10.6 8,453 10,333 5,136 7,016 18.14 24.78 DCF / LP Unit 2019E $2.71 7.8x 9.4x $9,263 $10,544 $5,947 $7,227 $21.00 $25.53 2020E 2.65 7.3 9.2 8,759 10,178 5,442 6,862 19.22 24.24 Selected Reference Range $19.90 $25.10 Source: Bison Projections, Public Filings and Wall Street Research. Market data as of 6/14/2019. (1) Indicative yield as of market date. (2) Selected reference range rounded to nearest $0.05; based on low of selected peers atlow-end and median of selected peers athigh-end, excluding outlier ET. (3) Based on Thunder net debt of $3,317 and 283.101 million fully diluted shares. 3 (4) MPLX shown pro forma for ANDX transaction. DCF and DPU CAGRs represent 2019-2020 growth. (5) Thunder Debt / EBITDA includes proportionate REX debt and EBITDA.

Preliminary and Confidential – Subject to Further Review and Revision Preliminary Discounted Cash Flow Analysis – CAFD/Share Cash Flow Summary – Bison Projections Fiscal Year Ending December 31, Terminal ($ in millions) 2H 2019E 2020E 2021E 2022E Period Asset EBITDA $257 $594 $654 $722 $722 (+) REX Distributions 229 385 362 356 356 (–) Cash Interest (87) (197) (220) (242) (242) (–) Cash Taxes 0 0 0 0 0 (–) Maintenance Capex (16) (35) (36) (36) (36) (–) Other 0 0 0 0 0 Cash Available for Dividends — $383 $746 $760 $801 $801 (x) Coverage 1.00x 1.00x 1.00x 1.00x 1.00x Average Shares Outstanding 283.101 283.101 283.101 283.101 283.101 CAFD / Share — $1.35 $2.64 $2.69 $2.83 $2.83 % Grow th — (2.6%) 1.9% 5.3% — Selected Reference Range Terminal Price / DCF Multiple Terminal Price / DCF Multiple 7.8x 8.2x 8.6x 9.0x 9.4x 7.8x 8.2x 8.6x 9.0x 9.4x Terminal Value Terminal Value $21.95 $23.13 $24.31 $25.49 $26.67 $21.95 $23.13 $24.31 $25.49 $26.67 Implied Equity Value Implied Equity Value Implied Perpetuity Grow th Rate 8.8% $24.53 $25.41 $26.29 $27.17 $28.05 8.8% (3.6%) (3.0%) (2.5%) (2.0%) (1.6%) quit y 9.5% 24.11 24.97 25.83 26.69 27.55 quit y 9.5% (3.0) (2.5) (1.9) (1.5) (1.0) E 10.1% 23.70 24.54 25.38 26.23 27.07 E 10.1% (2.4) (1.9) (1.3) (0.9) (0.4) of of 10.8% 23.30 24.12 24.95 25.77 26.60 10.8% (1.9) (1.3) (0.8) (0.3) 0.2 Cost 11.4% 22.91 23.71 24.52 25.33 26.14 Cost 11.4% (1.3) (0.7) (0.2) 0.3 0.8 Selected Reference Range: $22.90—$28.05 Source: Bison projections. Note: Cash flows discounted to 6/30/2019. Selected reference range rounded to nearest $0.05. Selected Terminal Price / DCF Multiple based on low to median of selected public company 4 comparables, excluding outlier ET. DCF does not include deduct for future tax liabilities. Subject to further diligence.

Preliminary and Confidential – Subject to Further Review and Revision Preliminary Discounted Cash Flow Analysis – CAFD/Share Cash Flow Summary – Research Projections Fiscal Year Ending December 31, Terminal ($ in millions) 2H 2019E 2020E 2021E 2022E Period Asset EBITDA $505 $946 $989 $1,034 $1,034 (–) Cash Interest (86) (194) (205) (216) (216) (–) Cash Taxes 0 0 0 0 0 (–) Maintenance Capex (19) (36) (37) (39) (39) Cash Available for Dividends — $400 $717 $746 $779 $779 (x) Coverage 1.00x 1.00x 1.00x 1.00x 1.00x Average Shares Outstanding 283.101 283.101 283.101 283.101 283.101 CAFD / Share — $1.41 $2.53 $2.64 $2.75 $2.75 % Grow th — (10.4%) 4.1% 4.3% — Selected Reference Range Terminal Price / DCF Multiple Terminal Price / DCF Multiple 7.8x 8.2x 8.6x 9.0x 9.4x 7.8x 8.2x 8.6x 9.0x 9.4x Terminal Value Terminal Value $21.35 $22.50 $23.65 $24.79 $25.94 $21.35 $22.50 $23.65 $24.79 $25.94 Implied Equity Value Implied Perpetuity Grow th Rate 8.8% $23.95 $24.80 $25.66 $26.51 $27.37 8.8% (3.6%) (3.0%) (2.5%) (2.0%) (1.6%) y y quit 9.5% 23.54 24.37 25.21 26.05 26.89 quit 9.5% (3.0) (2.5) (1.9) (1.5) (1.0) E 10.1% 23.14 23.96 24.78 25.60 26.42 E 10.1% (2.4) (1.9) (1.3) (0.9) (0.4) of of 10.8% 22.75 23.55 24.35 25.15 25.96 10.8% (1.9) (1.3) (0.8) (0.3) 0.2 Cost 11.4% 22.36 23.15 23.94 24.72 25.51 Cost 11.4% (1.3) (0.7) (0.2) 0.3 0.8 Selected Reference Range: $22.35—$27.35 Source: Research projections. Note: Cash flows discounted to 6/30/2019. Selected reference range rounded to nearest $0.05. Selected Terminal Price / DCF Multiple based on low to median of selected public company 5 comparables, excluding outlier ET. DCF does not include deduct for future tax liabilities. Subject to further diligence.

Preliminary and Confidential – Subject to Further Review and Revision Preliminary Discounted Cash Flow Analysis – Unlevered FCF Cash Flow Summary – Bison Projections Fiscal Year Ending December 31, Terminal ($ in millions) 2H 2019E 2020E 2021E 2022E Period Asset EBITDA $257 $594 $654 $722 $722 (+) REX Distributions 229 385 362 356 356 (–) Cash Taxes 0 0 0 0 0 (–) Maintenance Capex (16) (35) (36) (36) (36) (–) Other 0 0 0 0 0 (–) Grow th Capex (272) (455) (461) (400) (400) Unlevered Free Cash Flow — $198 $489 $519 $642 $642 Selected Reference Range Terminal Value / EBITDA Multiple Terminal Value / EBITDA Multiple 9.6x 9.9x 10.3x 10.6x 10.9x 9.6x 9.9x 10.3x 10.6x 10.9x Terminal Value Terminal Value $10,336 $10,698 $11,060 $11,422 $11,784 $10,336 $10,698 $11,060 $11,422 $11,784 Implied Equity Value Implied Perpetuity Grow th Rate 7.8% $22.05 $23.03 $24.01 $25.00 $25.98 7.8% 1.5% 1.7% 1.9% 2.0% 2.2% 8.1% 21.74 22.71 23.69 24.66 25.64 8.1% 1.8 2.0 2.2 2.3 2.5 CC CC A 8.4% 21.44 22.40 23.36 24.33 25.29 A 8.4% 2.1 2.3 2.4 2.6 2.8 W W 8.7% 21.13 22.09 23.05 24.00 24.96 8.7% 2.3 2.5 2.7 2.9 3.1 9.0% 20.84 21.78 22.73 23.68 24.62 9.0% 2.6 2.8 3.0 3.2 3.4 Selected Reference Range: $20.85—$26.00 Source: Bison projections. Note: Cash flows discounted to 6/30/2019. Selected reference range rounded to nearest $0.05. Selected Terminal Value / EBITDA Multiple based on low to median of selected public company 6 comparables, excluding outlier ET. Assumes share count of 283.101mm shares and net debt of $3,317. DCF does not include deduct for future tax liabilities. Subject to further diligence.

Preliminary and Confidential – Subject to Further Review and Revision Preliminary Discounted Cash Flow Analysis – Unlevered FCF Cash Flow Summary – Research Projections Fiscal Year Ending December 31, Terminal ($ in millions) 2H 2019E 2020E 2021E 2022E Period Asset EBITDA $505 $946 $989 $1,034 $1,034 (–) Cash Taxes 0 0 0 0 0 (–) Maintenance Capex (19) (36) (37) (39) (39) (–) Other 0 0 0 0 0 (–) Capex (176) (300) (300) (300) (300) Unlevered Free Cash Flow — $310 $610 $652 $695 $695 Selected Reference Range Terminal Value / EBITDA Multiple Terminal Value / EBITDA Multiple 9.6x 9.9x 10.3x 10.6x 10.9x 9.6x 9.9x 10.3x 10.6x 10.9x Terminal Value Terminal Value $9,911 $10,258 $10,605 $10,953 $11,300 $9,911 $10,258 $10,605 $10,953 $11,300 Implied Equity Value Implied Perpetuity Grow th Rate 7.8% $22.23 $23.17 $24.12 $25.06 $26.00 7.8% 0.7% 0.9% 1.2% 1.4% 1.5% C 8.1% 21.93 22.86 23.80 24.73 25.66 C 8.1% 1.0 1.2 1.4 1.6 1.8 WAC 8.4% 21.63 22.56 23.48 24.41 25.33 WAC 8.4% 1.3 1.5 1.7 1.9 2.1 8.7% 21.34 22.25 23.17 24.08 25.00 8.7% 1.6 1.8 2.0 2.2 2.4 9.0% 21.05 21.95 22.86 23.77 24.67 9.0% 1.9 2.1 2.3 2.5 2.7 Selected Reference Range: $21.05—$26.00 Source: Research projections. Note: Cash flows discounted to 6/30/2019. Selected reference range rounded to nearest $0.05. Selected Terminal Value / EBITDA Multiple based on low to median of selected public company 7 comparables, excluding outlier ET. Assumes share count of 283.101mm shares and net debt of $3,317. DCF does not include deduct for future tax liabilities. Subject to further diligence.

Preliminary and Confidential – Subject to Further Review and Revision Selected 100% Cash Precedent Transactions 100% Cash Deals – Midstream Energy Initial—Premium to Final Offer -Announcement Unaffected Unaffected Premium to Unaffected Target Acquiror Date Date Deal Value ($bn)1-day1-day1-w eek1-month Buckeye Partners, LP IFM Advisors 5/10/2019 5/9/2019 $10.3 — 27.5% 24.9% 23.3% American Midstream Partners * Arclight Capital 3/18/2019 9/27/2018 1.9 6.1% (8.7) (9.9) (14.8) TransMontaigne Partners LP * Arclight Capital 11/26/2018 7/9/2018 1.2 5.2 13.5 11.9 9.0 Arc Logistics Partners LP Zenith Energy LP 8/29/2017 8/28/2017 0.7 — 15.2 15.5 10.9 PennTex * Energy Transfer Partners 5/19/2017 5/18/2017 15.1 — 20.1 19.4 19.5 VTTI Energy Partners LP * VTTI BV 5/8/2017 3/2/2017 0.8 1.9 6.0 5.8 5.9 Worldpoint Terminals LP * Worldpoint Terminals Inc 4/4/2017 4/3/2017 0.8 — 5.8 6.4 3.7 Midcoast Energy Partners LP * Enbridge 1/27/2017 1/26/2017 0.5 — (8.6) (6.7) 7.1 Columbia Pipeline * Transcanada 11/1/2016 9/23/2016 13.9 — 11.1 11.9 20.0 Columbia Pipeline Group Inc. Transcanada 3/17/2016 3/10/2016 13.0 — 19.0 27.8 42.5 Hiland Partners LP * Management / Sponsor 1/15/2009 1/14/2009 0.6 (1.9) 26.6 22.4 49.1 Kinder Morgan * Management / Sponsor 5/29/2006 5/26/2006 21.6 18.5 27.4 28.8 23.2 High(1) $15.1 18.5% 27.4% 28.8% 49.1% Median(1) 1.2 5.2 11.1 11.9 9.0 Mean(1) 4.9 6.0 10.4 10.0 13.6 Low (1) 0.5 (1.9) (8.7) (9.9) (14.8) Reference Range(2) Metric Selected Range Implied Value per Share Premiums Paid Low High Low High1-Day $21.76 0.0% 25.0% $21.76 $27.201-Week 21.76 0.0 25.0 21.76 27.201-Month 21.76 0.0 25.0 21.76 27.20 Selected Reference Range $21.75 $27.20 Source: Public filings, FactSet, Market data as of 6/14/2019. (1) Includes related party deals only. 8 (2) Selected reference range rounded to nearest $0.05; based on Midstream Energy transactions marked with *.

Preliminary and Confidential – Subject to Further Review and Revision Diversified Illustrative WACC Calculation Cost of Net Debt-Related Metrics Capital Structure Value of Market Value Net Debt / Total Current Statutory Long Term WACC Calculation Inputs Name Net Debt of Equity Capital Ratio Marginal Tax Rate Yield Enterprise Products Partners LP $26,777 $64,483 29.3% — 3.2% Energy Transfer, LP 45,351 51,810 46.7 — 4.0 Target Capital Structure (Net Debt / Total Capital): 30.0 – 40.0 % Williams Companies 21,136 34,109 38.3 — 3.4 TC Energy Corporation 37,209 49,799 42.8 — 3.8 Median Capital Structure of Selected Companies: 36.6 % ONEOK, Inc. 10,284 26,753 27.8 21 3.7After-Tax Cost of Debt: 5.4 % Kinder Morgan Inc. 35,609 48,024 42.6 21 4.7 Enbridge Inc. 47,116 78,415 37.5 — 3.4 Expected Long-Term Yield: 5.4 % MPLX LP 18,383 35,000 34.4 — 3.8 Targa Resources Corp. 5,712 12,965 30.6 21 5.3 – Current Statutory Marginal Tax Rate: — % DCP Midstream Partners 5,360 6,498 45.2 — 4.8 Cost of Equity: 5.5% Equity Market Risk Premium 8.8 – 9.9 % Plains All American Pipeline LP 8,890 19,980 30.8 — 3.8 Thunder 3,317 6,608 33.4 — 5.4 6.7% Equity Market Risk Premium 10.2 – 11.4 % High $47,116 $78,415 46.7% 5.4% Median 19,760 34,555 36.0 3.8 Risk Free Rate(30-Year Treasury Bond): 2.6 % Mean 22,095 36,204 36.6 4.1 Low 3,317 6,498 27.8 3.2 Assumed Equity Market Risk Premium—low : 5.5 % Cost of Equity-Related Metrics Assumed Equity Market Risk Premium—high: 6.7 % Adjusted Beta Equity Beta Estimation High Debt Unlevering Unlevered (Bloomberg) Period (Yrs) Yield Issuer Beta Tax Rate Asset Beta Relevered Equity Beta: 1.13 – 1.32 Enterprise Products Partners LP 1.018 5.0 0.0 — 0.719 – Unlevered Asset Beta: 0.79 Energy Transfer, LP 1.558 5.0 0.0 — 0.831 – Selected “Standard” Beta Measurement Period (Years): 5 Williams Companies 1.508 5.0 0.0 — 0.931 – Implied Net Debt / Equity Ratio: 42.9 – 66.7 % TC Energy Corporation 1.008 5.0 0.0 — 0.577 ONEOK, Inc. 1.325 5.0 0.0 31 1.047 Small Cap Risk Premium: 0.0 % Kinder Morgan Inc. 1.118 5.0 0.0 31 0.739 High Yield Issuer? (Y / N) Enbridge Inc. 1.010 5.0 0.0 — 0.631 MPLX LP 1.062 5.0 0.0 — 0.696 Weighted Average Cost of Capital: 7.8 – 9.0 % Targa Resources Corp. 1.579 5.0 Y 0.3 31 1.281 DCP Midstream Partners 1.301 5.0 0.0 — 0.713 5.5% Equity Market Risk Premium 7.8 – 8.1 % Plains All American Pipeline LP 1.089 5.0 0.0 — 0.753 6.7% Equity Market Risk Premium 8.7 – 9.0 % Thunder 1.040 5.0 Y 0.3 — 0.793 The low end of the WACC is based upon the low end of the equity market Median (All Companies) 1.10 0.75 Median (Excl. * Companies) 1.10 0.75 risk premium (5.5%) and the high end of the net debt / total capital ratio. Mean (All Companies) 1.22 0.81 The high end is based on the high end of the equity market risk premium Mean (Excl. * Companies) 1.22 0.81 (6.7%) and the low end of the capital structure. High 1.58 1.28 Low 1.01 0.58 Unlevering tax rate represents a blended average tax rate based on the number of days for w hich different statutory marginal tax rates w ere in effect during the beta estimation period. * Beta estimation period differs from standard period of 5 years used in the analysis 9 Source: FactSet, Bloomberg, Public filings. Note: Market-based metrics as of 6/14/2019.

Appendix

Preliminary and Confidential – Subject to Further Review and Revision Illustrative Future Tax Liability Analysis Projected Tax Liability 2028 DCF / Share $3.75 Tax Rate 21.0% Terminal PV of Multiple Taxes/Share 6/30/2019 6/30/2020 6/30/2021 6/30/2022 6/30/2023 6/30/2024 6/30/2025 6/30/2026 6/30/2027 6/30/2028 12/31/2028 6.0x $2.19 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $0.00 $4.73 7.0 2.56 -—————————- 5.52 8.0 2.93 -—————————- 6.30 8.6 3.15 -—————————- 6.78 9.0 3.29 -—————————- 7.09 10.0 3.66 -—————————- 7.88 11.0 4.02 -—————————- 8.67 Source: Bison projections. Note: Based on Thunder expectation not to pay cash federal income taxes for a period currently estimated to be at least 10 years, beginning 2019. Cash flows discounted to 6/30/2019. Selected midpoint 10 Terminal Price / DCF Multiple based on low to median of selected public company comparables, excluding outlier ET. Subject to further diligence. Future liability discounted at 8.40% midpoint of WACC range.

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Any estimates included herein constitute our judgment as of the date hereof and are subject to change without any notice. We and/or our affiliates may make a market in these instruments for our customers and for our own account. Accordingly, we may have a position in any such instrument at any time. Although this material may contain publicly available information about Citi corporate bond research, fixed income strategy or economic and market analysis, Citi policy (i) prohibits employees from offering, directly or indirectly, a favorable or negative research opinion or offering to change an opinion as consideration or inducement for the receipt of business or for compensation; and (ii) prohibits analysts from being compensated for specific recommendations or views contained in research reports. So as to reduce the potential for conflicts of interest, as well as to reduce any appearance of conflicts of interest, Citi has enacted policies and procedures designed to limit communications between its investment banking and research personnel to specifically prescribed circumstances. © 2019 Citigroup Inc. All rights reserved. Citi and Citi and Arc Design are trademarks and service marks of Citigroup Inc. or its affiliates and are used and registered throughout the world. Citi believes that sustainability is good business practice. We work closely with our clients, peer financial institutions, NGOs and other partners to finance solutions to climate change, develop industry standards, reduce our own environmental footprint, and engage with stakeholders to advance shared learning and solutions. Highlights of Citi’s unique role in promoting sustainability include: (a) releasing in 2007 a Climate Change Position Statement, the first US financial institution to do so; (b) targeting $50 billion over 10 years to address global climate change: includes significant increases in investment and financing of renewable energy, clean technology, and other carbon-emission reduction activities; (c) committing to an absolute reduction in GHG emissions of all Citi owned and leased properties around the world by 10% by 2011; (d) purchasing more than 234,000 MWh of carbon neutral power for our operations over the last three years; (e) establishing in 2008 the Carbon Principles; a framework for banks and their U.S. power clients to evaluate and address carbon risks in the financing of electric power projects; (f) producing equity research related to climate issues that helps to inform investors on risks and opportunities associated with the issue; and (g) engaging with a broad range of stakeholders on the issue of climate change to help advance understanding and solutions. Citi works with its clients in greenhouse gas intensive industries to evaluate emerging risks from climate change and, where appropriate, to mitigate those risks. efficiency, renewable energy and mitigation 11