
Quarterly Investor Relations Presentation At and for the three months ended December 31, 2017

About GWB 2 Company Snapshot Exchange / Ticker • NYSE: GWB Market Cap • 58.9 million shares outstanding / $2.41 billion Ownership • 100% publicly traded Total Assets • $11.81 billion ROA / ROTCE • 1.00% / 11.6% (each impacted by a $13.6 million one-time deferred tax adjustment) Efficiency Ratio • 45.8% FTEs • Approximately 1,700 Locations • 173 branches in nine states Business & Ag Expertise • 89% of loans in business and ag segments; 6 th largest farm lender bank in the U.S.(1) (1) As of September 30, 2017. Source: American Banker's Association NOTE: All financial data is as of or for the three months ended December 31, 2017 unless otherwise noted. Market Cap calculated based on January 8, 2018 closing price of $40.97. Branch count as of December 31, 2017. See appendix for non-GAAP reconciliation of ROTCE and efficiency ratio.

Footprint 3 • 173 banking branches across nine Midwestern and Western states • Vibrant, diverse economies balanced across growing commercial hub cities and smaller rural communities • Opportunities for expansion into new markets within and adjacent to footprint Attractive Markets

Executing on Strategy (1) This is a non-GAAP measure. See appendix for reconciliation. 4 Focused Business Banking Franchise with Agribusiness Expertise Strong Profitability and Growth Driven by a Highly Efficient Operating Model Risk Management Driving Strong Credit Quality Strong Capital Generation and Attractive Dividend • All regulatory capital ratios remain above minimums to be considered “well capitalized” • Strong capital generation supports a quarterly dividend of $0.20 per share ◦ Dividend payable February 21, 2018 to stockholders of record as of the close of business on February 9, 2018 • Total loans increased $196.8 million during the quarter representing 8.7% annualized growth • Loan growth was focused in the commercial real estate and agriculture segments of the portfolio, with the majority of agriculture growth driven by short-term advances for tax planning purposes • Deposit balances increased by $46.6 million compared to September 30, 2017 • Fully diluted EPS of $0.49 and adjusted EPS of $0.72 for the quarter compared to $0.64 for 4QFY17, an increase of 12.5% • The effective tax rate, excluding one-time revaluation of deferred tax assets, declined to 26.0%, contributing to higher profitability • Efficiency ratio(1) of 45.8% for the quarter compared to 47.1% for the prior quarter • Net charge-offs of $4.0 million during the quarter represent 0.18% of average total loans on an annualized basis, the lowest quarterly rate since FY16 • Loans graded "Substandard" increased by 6.4% to $247.7 million, loans graded "Watch" decreased by 7.7% to $287.5 million and nonaccrual loans increased by 6.5% to $147.3 million compared to September 30, 2017

Non-Executive Officers 9 Experienced Management Team Prior experience – Senior Human Resource Generalist for Citibank and Wells Fargo 39 41 35 24 18 34 30 16 11 9 14 28 4 Ken Karels Chairman, President and CEO Doug Bass Regional President Regional President for Iowa / Kansas / Missouri, Arizona / Colorado, L&D / Marketing, Operations, and People & Culture Prior positions with U.S. Bank and First American Bank Group Pete Chapman Executive VP & CFO Responsible for financial / regulatory reporting, planning and strategy, project management, treasury, and banking operations in Minnesota and North Dakota Prior U.S. experience with E&Y Steve Ulenberg Executive VP & CRO Responsible for risk framework across Great Western Prior leadership roles in commercial and wholesale banking, risk management, and cross-organizational strategy – National Australia Bank Executive Officers Former COO and Regional President – Great Western Former President and CEO – Marquette Bank Acting Regional President for South Dakota Prior experience – VP & Regional Training Manager for Bank of the West and VP Learning and Development Officer for Community First Bankshares Inc Cheryl Olson Head of Marketing Industry experience (yrs) Great Western Bank experience (yrs) (1) Andy Pederson Head of People & Culture and L&D Donald Straka General Counsel and Corporate Secretary Prior experience – attorney and executive in banking, securities and M&A 5(1) For Messers. Chapman and Ulenberg, includes experience at National Australia Bank, Ltd. and subsidiaries; For Mr. Erkonen, includes experience at HF Financial Corp. Scott Erkonen Chief Information Officer Prior leadership role representing the United States internationally in the areas of IT Governance and Information Security -- ISO (International Organization for Standardization) 22 11 Michael Gough Executive VP & CCO Prior leadership roles with GWB include Senior Lender, EVP - Credit, and Executive GM - Strategic Business Services 35 22

$12.0 $10.0 $8.0 $6.0 $4.0 $2.0 $0.0 '06 '07 '08 '09 '10 '11 '12 '13 '14 '15 '16 '17 1QFY18 $4.3 $8.2 $9.1 $9.4 $9.8 $11.7 $11.8 $3.1 $3.4 $5.2 $8.3 $9.0 $11.5 Acquisition History Note: Total assets are as of September 30 of each fiscal year unless otherwise noted. Acquired assets are the total of the fair value of total assets acquired and the net cash and cash equivalents received, at the time of acquisition of each indicated year. 6 Acquired Security Bank ($0.1 billion) Acquired Sunstate Bank and three branches from HF Financial Corp. ($0.2 billion total) Acquired North Central Bancshares Inc. ($0.4 billion total) Acquired HF Financial Corp. ($1.1 billion total) Acquired First Community Bank's Colorado franchise and a branch from Wachovia ($0.6 billion total) Acquired F&M Bank-Iowa and TierOne Bank ($3.0 billion total) Pre-Acquisition Assets Acquired Assets

Loan Portfolio Composition 7 Loan Portfolio ($MM) At September 30 of each fiscal year unless otherwise noted (UPB). Geographic Diversification Iowa / Kansas / Missouri 28.7% South Dakota 24.4% Nebraska 16.9% Arizona 13.9% Colorado 12.2% Minnesota / North Dakota 2.6% Other 1.3% NOTE: Other loans represent acquired workout loans and certain other loans managed by our staff FY11 FY12 FY13 FY14 FY15 FY16 FY17 1QFY18 $2,342 $2,364 $2,312 $2,541 $2,846 $3,754 $4,125 $4,296 $1,092 $1,396 $1,587 $1,681 $1,861 $2,169 $2,122 $2,177 $971 $1,354 $1,482 $1,571 $1,611 $1,673 $1,719 $1,696 $777 $940 $906 $902 $922 $1,021 $933 $924 $5,293 $6,197 $7,351 $8,736 Focused business and ag lending growth Commercial RE Agriculture C&I Residential RE Consumer & Other $6,820 $6,414 Portfolio Segmentation by Type $9,202$9,009 Commercial non- real estate, 18.4% Ag real estate, 10.8% Ag operating, 12.9% Construction & development, 6.8% Owner-occupied CRE, 14.3% Non owner-occupied CRE, 22.1% Multifamily, 3.5% Residential real estate, 10.0% Consumer & Other, 1.2%

Additional Loan Information 8 Incremental Impact from Acquired Loans ($MM)Highlights (1) Comprehensive Credit-Related Coverage is a non-GAAP measure that Management believes is useful to demonstrate that the FV adjustments related to credit and remaining loan discounts consider credit risk and should be considered as part of total coverage. • Loan portfolio is managed to Board-approved concentration limits and regulatory guidelines • All categories are within limits including regulatory 300/100% of capital CRE limits • Income statement impact from acquired loans (including indemnification asset amortization) has not significantly inflated earnings and is not expected to in the future • Management remains very comfortable with credit coverage levels Includes ASC 310-20 accretion, ASC 310-30 accretion in excess of contractual interest and indem. asset amortization ASC 310-30 Non ASC 310-30 2014 2015 2016 2017 FY18 YTD $(5.6) $0.5 $1.4 $3.1 $1.3 $0.2 $(3.3) $2.1 $2.1 $0.2 GWB Legacy - Loans at Amortized Cost GWB Legacy - Loans at Fair Value HF Financial Corp. Acquired Loans Other Acquired Loans Total ALLL $ 60,798 $ — $ 907 $ 2,318 $ 64,023 Remaining Loan Discount $ — $ — $ 17,256 $ 9,280 $ 26,536 Fair Value Adjustment (Credit) $ — $ 6,180 $ — $ — $ 6,180 Total ALLL / Discount / FV Adj. $ 60,798 $ 6,180 $ 18,163 $ 11,598 $ 96,739 Total Loans $ 7,413,714 $ 980,144 $ 624,796 $ 146,719 $ 9,165,373 ALLL / Total Loans 0.82% —% 0.15% 1.58% 0.70% Discount / Total Loans —% —% 2.76% 6.33% 0.29% FV Adj. / Total Loans —% 0.63% —% —% 0.07% Total Coverage / Total Loans (1) 0.82% 0.63% 2.91% 7.91% 1.06% Comprehensive Credit-Related Coverage ($MM)

Focused CRE Lending 9 Highlights CRE Portfolio Composition by Type (UPB $MM) CRE Portfolio Exposure Sizes (UPB) CRE Net Charge-offs / Average Loans (1) ($MM) NOTE: All customer references are aggregated based on CIF and do not group CIFs with related ownership groups. Industry disclosures based on NAICS codes. (1) Net charge-offs / average loans represent charge-offs, net of recoveries, as a percent of average loans for each period. Average loans are calculated as the two point average of each period. Ratios annualized for partial-year periods. • Focus on commercial property investors, owner-occupied properties, multi-family property investors and a diverse range of commercial construction with limited exposure to land development and other speculative projects • Continued customer demand to finance CRE construction and development, especially in larger markets within our footprint • Regulatory CRE levels of 252% (300% test) and 63% (100% test) • 10 largest CRE exposures represent 8.0% of total CRE and average $34 million $15M+: 20.9% $5M- $15M: 36.3% $1M - $5M: 30.6% $250K - $1M: 9.4% <$250K: 2.8% Construction and development, 14.5%, $623.0 Owner-occupied CRE, 30.7%, $1,317.6 Non-owner- occupied CRE, 47.4%, $2,036.0 Multifamily, 7.4%, $319.1 FY11 FY12 FY13 FY14 FY15 FY16 FY17 FY18 YTD 1.3% 0.9% 0.8% 0.1% —% 0.1% 0.04% 0.02% $32.10 $21.59 $18.96 $1.73 $0.63 $2.91 $1.55 $0.18

Diverse C&I Exposure 10 Highlights C&I Portfolio Composition by Industry (UPB) C&I Portfolio Exposure Sizes (UPB) C&I Net Charge-offs / Average Loans (1) ($MM) NOTE: All customer references are aggregated based on CIF and do not group CIFs with related ownership groups. Industry disclosures based on NAICS codes. (1) Net charge-offs / average loans represent charge-offs, net of recoveries, as a percent of average loans for each period. Average loans are calculated as the two point average of each period. Ratios annualized for partial-year periods. • Diverse range of industry exposure across C&I lending portfolio, including healthcare, tourism & hospitality, freight & transport and agribusiness-related services • 10 largest C&I exposures represent 19.7% of total C&I and average $33 million • Approximately 4,100 customers with an average exposure of $412,000 FY11 FY12 FY13 FY14 FY15 FY16 FY17 FY18 YTD 0.9% 0.5% 0.2% 0.3% 0.5% 0.1% 0.7% 0.3% $8.33 $5.92 $2.43 $3.94 $7.75 $1.20 $11.88 $1.12 $15M+: 25.5% $5M- $15M: 26.4% $1M - $5M: 27.9% $250K - $1M: 11.9% <$250K: 8.3% 8.3% 5.9% 3.1% 3.6% 5.8% 2.1% 2.1% 69.1% Med / Surg Hospitals Nursing Care Facilities Casino Hotels Trucking Retirement Communities Residential Warehouse Lending Farm & Garden Equip Wholesalers Other

Ag Loan Portfolio 11 Highlights Ag Portfolio Composition by Industry (UPB) Ag Net Charge-offs / Average Loans (1) ($MM)Ag Portfolio Exposure Sizes (UPB) NOTE: All customer references are aggregated based on CIF and do not group CIFs with related ownership groups. Industry disclosures based on NAICS codes. (1) Net charge-offs / average loans represent charge-offs, net of recoveries, as a percent of average loans for each period. Average loans are calculated as the two point average of each period. Ratios annualized for partial-year periods. • Portfolio balanced across subsegments • 10 largest Ag exposures represent 13.0% of total Ag and average $28 million • Approximately 3,300 customers with an average exposure size of $666,000 • Grain producers' 2017 results generally in line with expectations and risk rating changes are minimal ◦ Producers not willing to adjust their business to lower commodity prices are not a fit for GWB Grains, 30.4% Beef Cattle, 22.9% Dairy Farms, 25.8% Hogs, 5.3% Other Specialty, 15.6% Grains 30% Proteins 54% Other 16% $15M+: 17.4% $5M- $15M: 33.2% $1M - $5M: 27.6% $250K - $1M: 14.8% <$250K: 7.0% FY11 FY12 FY13 FY14 FY15 FY16 FY17 FY18 YTD 0.1% —% 0.3% 0.1% —% 0.2% 0.3% 0.4% $0.87 $(0.11) $4.05 $2.37 $0.48 $3.74 $7.40 $2.15

FHLB & Other Borrowings - 1.76% WA Cost Securities sold under agreements to repurchase - 0.30% WA Cost Subordinated debentures and subordinated notes payable - 4.28% WA Cost Investments & Borrowings 12 • Portfolio composition has transitioned significantly over the last 3 years away from heavy GNMA concentration • Investment portfolio weighted average life of 3.6 years as of December 31, 2017 and yield of 1.97% for the quarter ended December 31, 2017, an increase of 11 basis points compared to the prior quarter • Borrowings portfolio had a cost of 1.76% for the quarter ended December 31, 2017, an increase of 16 basis points compared to the prior quarter Investment Portfolio Borrowings & Weighted Average Cost Highlights U.S. Treasuries, 17% GNMA, 35% Other MBS, 43% States and political subdivisions, 5%

Non-Interest- Bearing Demand 21.4% NOW, MMDA and Savings 64.7% Time certificates $250K+ 3.0% Other time certificates 10.9% Deposits 13 Portfolio Segmentation by Type Portfolio Over Time ($MM) Geographic Diversification NOTE: South Dakota and Other deposits include a small amount of deposits managed by our Corporate staff. At September 30 of each fiscal year unless otherwise noted. FY11 FY12 FY13 FY14 FY15 FY16 FY17 1QFY18 $848 $1,076 $1,199 $1,303 $1,368 $1,881 $1,856 $1,932 $2,532 $3,037 $3,602 $4,005 $4,638 $5,343 $5,847 $5,838$2,891 $6,271 $2,771 $6,884 $2,147 $6,948 $1,744 $7,052 $1,380 $7,386 $1,381 $8,605 $1,275 $8,978 $1,254 $9,024 Portfolio transformation away from time deposits and to significant business deposit growth Non-Interest-Bearing Interest-Bearing Demand Time Iowa / Kansas / Missouri, 29.4%South Dakota and Other, 26.3% Nebraska, 27.0% Arizona, 4.5% Colorado, 12.3% North Dakota / Minnesota, 0.5% $7,387 $6,885 $6,272

Growth Metro vs Rural Metro and Rural Markets DepositsLoans • Historically, the Company's core Midwestern presence was focused in Iowa, Nebraska and South Dakota in rural markets largely supported by agricultural economies • M&A activity and de novo expansion over the last decade have expanded the footprint to include more metro1 markets • While loan and deposit balances in the core Midwestern markets remain critical to maintain, growth prospects are much more robust in Metro markets • Compound average growth over the last four years in metro markets has been 15% for loans and 9% for deposits, compared to 3% and 4%, respectively, in rural markets September 2013 $172 3% $3,649 60% $2,261 37% September 2017 $59 $6,340 $2,570 September 2013 $29 0% $3,235 47% $3,669 53% September 2017 $81 1% $4,591 51% $4,306 48% Metro Rural CorporateMetro Rural Corporate 1 Metro markets generally include MSAs with >100K populations 14 1% 28% 71%

Tangible equity net of DTAs and AOCI, 91.3%, $1,042.5 Eligible ALLL, 5.6%, $64.5 Eligible subordinated debt, 3.1%, $35.0 Capital 15 Summary Capital Priorities Capital Ratios Total Capital Composition ($MM) • Attractive dividend of $0.20 for the quarter ended December 31, 2017 (dividend yield of 2.0% based on avg. closing price during the quarter)(1) • All regulatory capital ratios remain above regulatory minimums to be considered “well capitalized” • Deferred tax adjustment reduced the total capital ratio by approximately 15 basis points (1) Future dividends subject to Board approval. (2) TCE/TA is a non-GAAP measure. See appendix for reconciliation. 1 2 3 Organic Growth & Compelling Dividend Yield Attractive and Accretive Acquisitions Share Buybacks Great Western Bancorp, Inc. Ratio Well Capitalized Minimum Difference to Well Capitalized Tier 1 capital 11.3% 8.0% 3.3% Total capital 12.3% 10.0% 2.3% Tier 1 leverage 10.3% 5.0% 5.3% Common equity tier 1 10.5% 6.5% 4% Tangible common equity / tangible assets (2) 9.2% Risk-weighted assets ($MM) $9,892 Great Western Bank Ratio Well Capitalized Minimum Difference to Well Capitalized Tier 1 capital 11.0% 8.0% 3.0% Total capital 11.7% 10.0% 1.7% Tier 1 leverage 10.0% 5.0% 5.0% Common equity tier 1 11.0% 6.5% 4.5% Risk-weighted assets ($MM) $9,890

• Management believes the balance sheet is well-positioned for the anticipated interest rate trajectory • Internal expense planning is not dependent on rate hikes and NIM expansion • Investment portfolio weighted average life of 3.6 years • Relatively short average tenor of the loan portfolio (1.2 years at December 31, 2017) due to: • Higher proportion of 12-month revolving lines of credit in line with business and agriculture lending focus • Certain fixed-rate loans with original terms greater than 5 years are swapped to floating Fixed, 36%, $3,346Variable (swapped), 11%, $980 Floating (not floored), 22%, $2,037 Variable (not floored), 29%, $2,638 Variable and Floating (floored), 2%, $154 • Average floored loan is 71 bps in the money • Floating: 51% Prime, 28% 5yr Tsy, 21% all other • Variable reprices within 1 month; Floating reprices greater than 1 month Interest Rate Sensitivity 16 Summary Loan Portfolio Behavior ($MM) Sensitivity Modeling Immediate Gradual 15.00% 10.00% 5.00% 0.00% -5.00% -10.00% -100 bps +100 bps +200 bps +300 bps +400 bps

FY13 FY14 FY15 FY16 FY17 1QFY18 $219 $288 $310 $328 $312 $287 $139 $358 $126 $414 $184 $494 $242 $570 $233 $545 $248 $535 5.6% 6.1% 6.7% 6.6% 6.1% 5.8% FY11 FY12 FY13 FY14 FY15 FY16 FY17 FY18 YTD 0.88% 0.54% 0.44% 0.14% 0.13% 0.12% 0.26% 0.18% (1) Comprehensive Credit-Related Coverage is a non-GAAP measure. See slide 8 for calculation. Asset Quality 17 Highlights Net Charge-offs / Average Total Loans Sound Credit QualityWatch & Substandard Loans ($MM) "Watch" and "Substandard" loans declined as a percentage of total loans Watch Loans Substandard Loans % of Total Loans NALs / Total Loans Reserves / NALs • Ratio of ALLL / total loans was 0.70% at December 31, 2017, a decrease from 0.71% at September 30, 2017 ◦ Comprehensive Credit-Related Coverage is 1.06%(1), inclusive of acquired loan marks and credit adjustment on loans at fair value • Nonaccrual loans increased by $9.0 million, loans graded “Watch” decreased $24.1 million and loans graded “Substandard” increased $14.8 million during the quarter ◦ Changes each primarily driven by deterioration of a small number of CRE loans ◦ Ag grain producer annual reviews underway with overall performance in line with expectations FY12 FY13 FY14 FY15 FY16 FY17 1QFY18 2.76% 2.03% 1.16% 0.93% 1.46% 1.54% 42.4% 43.3% 60.2% 83.8% 51.1% 45.9% 43.5% 1.61%

Goodwill & Intangible Assets 18 Goodwill ($MM) Other Intangible Assets ($MM) (1) (1) Balances and amortization expense at September 30 and for the respective fiscal years. Amounts for fiscal years 2018 – 2023 are forecast based on existing intangible assets and could change materially based on future acquisitions. • Majority (84%) of goodwill on GWB’s balance sheet resulted from the acquisition of GWB by National Australia Bank Ltd. in 2008 and was pushed down to GWB’s balance sheet • Recognizing an impairment, which management does not believe currently exists, is the only opportunity to eliminate the NAB-related goodwill • Existing intangible assets and related amortization have become minimal • Future M&A activity could generate additional assets and amortization expense NAB acquisition of GWB, $622 HF Financial, $41 GWB acquisitions pre-IPO, $76 $20.0 $15.0 $10.0 $5.0 $0.0 $20.0 $18.0 $16.0 $14.0 $12.0 $10.0 $8.0 $6.0 $4.0 $2.0 $0.0 201 4 201 5 201 6 201 7 201 8 201 9 202 0 202 1 202 2 202 3 Year-end balance (left axis) Annual amortization (right axis)

Income Statement Summary

Net Interest Income (FTE) NIM (FTE) Adjusted NIM (FTE) Revenue 20 Revenue Highlights Net Interest Income ($MM) and NIM Noninterest Income (1) (2) (1) Chart excludes changes related to loans and derivatives at fair value which netted $(1.4) million for the quarter. Dollars in thousands. (2) Adjusted NIM (FTE) is a non-GAAP measure. See appendix for reconciliations. Service charges and other fees, $13,178 Wealth management, $2,185 Mortgage banking income, net, $1,660 Other, $1,090 1QFY17 4QFY17 1QFY18 $99.0 $101.8 $102.2 3.82% 3.93% 3.89% 3.65% 3.82% 3.80% NIM Analysis • Net interest income (FTE) up 0.4% compared to 4QFY17 primarily due to higher loan interest income driven by growth in average loans outstanding • NIM (FTE) down 4 basis points and adjusted NIM (FTE) (2) down 2 basis points on a sequential quarter basis ◦ Lower statutory tax rate reduced each metric by approximately 2 basis points (lower FTE adjustment) • Noninterest income, excluding the change in fair value of fair value option loans and the net gain (loss) on related derivatives, decreased 2% compared to 4QFY17 ◦ Primarily driven by full-quarter Durbin impact 3.80% 3.82% 0.11% -0.01% -0.02% -0.01% -0.01% 0.01% 3.93% 3.89% 0.09% 4QFY17 Investment yiel d FHLB yield FTE adjustment IB deposit yield Time deposit yield 1QFY18 NIM (FTE) Adjusted NIM (FTE) (2) Cost of swaps: 0.09% current quarter vs 0.10% prior quarter

1QFY17 2QFY17 3QFY17 4QFY17 1QFY18 $37 $35 $35 $38 $29 $14 $43 1.28% 1.26% 1.25% 1.30% 1.00% 1QFY17 4QFY17 1QFY18 $7.0 $4.7 $4.6 1QFY17 4QFY17 1QFY18 $51.8 $55.0 $54.9 $52.5 45.1% 47.1% 45.8% 21 Noninterest Expense ($MM) Earnings, Expenses & Provision Highlights Provision for Loan Losses ($MM) Net Income ($MM) (1) Efficiency ratio and adjusted net income are non-GAAP measures. See appendix for reconciliations. Noninterest Acquisition expense Efficiency Ratio (1) 0.8% decrease in total noninterest expense sequentially • Net income of $29.2 million included a one-time $13.6 million charge to provision for income taxes driven by the Tax Cuts and Jobs Act of 2017 ◦ Adjusted net income of $42.8 million represents a 13.7% quarter-over-quarter increase • Efficiency ratio(1) was 45.8%, down from 47.1% for 4QFY17 • Provision for loan losses stable compared to prior quarter • Effective tax rate of 26.0%, excluding one-time deferred tax adjustment, reflects the lower blended rate for FY18 Net Income Adjusted net income (1) ROAA

22 Proven Business Strategy Focused Business Banking Franchise with Agribusiness Expertise Risk Management Driving Solid Credit Quality Attract and Retain High-Quality Relationship Bankers Invest in Organic Growth While Optimizing Footprint Deepen Customer Relationships Strong Profitability and Growth Driven by a Highly Efficient Operating Model Strong Capital Generation and Attractive Dividend Explore Accretive Strategic Acquisition Opportunities

Disclosures 23 Forward-Looking Statements: This presentation contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Statements about Great Western Bancorp, Inc.’s expectations, beliefs, plans, strategies, predictions, forecasts, objectives, assumptions or future events or performance are not historical facts and may be forward-looking. These statements are often, but not always, made through the use of words or phrases such as “anticipates,” “believes,” “can,” “could,” “may,” “predicts,” “potential,” “should,” “will,” “estimate,” “plans,” “projects,” “continuing,” “ongoing,” “expects,” "views," “intends” and similar words or phrases. In particular, the statements included in this press release concerning Great Western Bancorp, Inc.’s expected performance and strategy, the effects of tax reform, the outlook for its agricultural lending segment and the interest rate environment, beyond fiscal year 2017 are not historical facts and are forward-looking. Accordingly, the forward-looking statements in this press release are only predictions and involve estimates, known and unknown risks, assumptions and uncertainties, that could cause actual results to differ materially from those expressed. All forward-looking statements are necessarily only estimates of future results, and there can be no assurance that actual results will not differ materially from expectations, and, therefore, you are cautioned not to place undue reliance on such statements. Any forward-looking statements are qualified in their entirety by reference to the factors discussed in the sections titled “Item 1A. Risk Factors” and "Cautionary Note Regarding Forward-Looking Statements" in Great Western Bancorp, Inc.’s Annual Report on Form 10-K for the fiscal year ended September 30, 2017. Further, any forward-looking statement speaks only as of the date on which it is made, and Great Western Bancorp, Inc. undertakes no obligation to update any forward-looking statement to reflect events or circumstances after the date on which the statement is made or to reflect the occurrence of unanticipated events. Non-GAAP Financial Measures: This presentation contains non-GAAP measures which our management relies on in making financial and operational decisions about our business and which exclude certain items that we do not consider reflective of our business performance. We believe that the presentation of these measures provides investors with greater transparency and supplemental data relating to our financial condition and results of operations. These non-GAAP measures should be considered in context with our GAAP results. A reconciliation of these non-GAAP measures appears in our earnings release dated January 25, 2017 and in Appendix 1 to this presentation. Our earnings release and this presentation are available in the Investor Relations section of our website at www.greatwesternbank.com. Our earnings release and this presentation are also available as part of our Current Report on Form 8-K filed with the SEC on January 25, 2017. Explanatory Note: In this presentation, all financial information presented refers to the financial results of Great Western Bancorp, Inc. combined with those of its predecessor, Great Western Bancorporation, Inc.

Appendix 1 Non-GAAP Measures

Non-GAAP Measures 25 At or for the three months ended: December 31, 2017 September 30, 2017 June 30, 2017 March 31, 2017 December 31, 2016 Adjusted net income and adjusted earnings per common share: Net income - GAAP $ 29,230 $ 37,662 $ 35,060 $ 35,162 $ 36,903 Add: Acquisition expenses, net of tax — — — — 440 Add: Deferred taxes revaluation 13,586 — — — — Adjusted net income $ 42,816 $ 37,662 $ 35,060 $ 35,162 $ 37,343 Weighted average diluted common shares outstanding 59,087,729 58,914,144 59,130,632 59,073,669 58,991,905 Earnings per common share - diluted $ 0.49 $ 0.64 $ 0.59 $ 0.60 $ 0.63 Adjusted earnings per common share - diluted $ 0.72 $ 0.64 $ 0.59 $ 0.60 $ 0.63 Tangible net income and return on average tangible common equity: Net income - GAAP $ 29,230 $ 37,662 $ 35,060 $ 35,162 $ 36,903 Add: Amortization of intangible assets, net of tax 376 380 488 500 676 Tangible net income $ 29,606 $ 38,042 $ 35,548 $ 35,662 $ 37,579 Average common equity $ 1,761,127 $ 1,740,429 $ 1,715,460 $ 1,686,770 $ 1,666,243 Less: Average goodwill and other intangible assets 748,144 748,571 749,074 749,638 750,290 Average tangible common equity $ 1,012,983 $ 991,858 $ 966,386 $ 937,132 $ 915,953 Return on average common equity * 6.6% 8.6% 8.2% 8.5% 8.8% Return on average tangible common equity ** 11.6% 15.2% 14.8% 15.4% 16.3% * Calculated as net income - GAAP divided by average common equity. Annualized for partial-year periods. ** Calculated as tangible net income divided by average tangible common equity. Annualized for partial-year periods.

Non-GAAP Measures At or for the three months ended: December 31, 2017 September 30, 2017 June 30, 2017 March 31, 2017 December 31, 2016 Adjusted net interest income and adjusted net interest margin (fully-tax equivalent basis): Net interest income - GAAP $ 100,622 $ 99,672 $ 96,888 $ 95,744 $ 96,891 Add: Tax equivalent adjustment 1,565 2,122 2,154 2,182 2,142 Net interest income (FTE) 102,187 101,794 99,042 97,926 99,033 Add: Current realized derivative gain (loss) (2,476) (2,714) (3,320) (3,875) (4,486) Adjusted net interest income (FTE) $ 99,711 $ 99,080 $ 95,722 $ 94,051 $ 94,547 Average interest-earning assets $ 10,412,882 $ 10,283,401 $ 10,124,404 $ 10,144,875 $ 10,286,284 Net interest margin (FTE) * 3.89% 3.93% 3.92% 3.91% 3.82% Adjusted net interest margin (FTE) ** 3.80% 3.82% 3.79% 3.76% 3.65% * Calculated as net interest income (FTE) divided by average interest earning assets. Annualized for partial-year periods. ** Calculated as adjusted net interest income (FTE) divided by average interest earning assets. Annualized for partial-year periods. Adjusted interest income and adjusted yield (fully-tax equivalent basis), on non ASC 310-30 loans: Interest income - GAAP $ 104,935 $ 102,998 $ 98,724 $ 97,170 $ 97,588 Add: Tax equivalent adjustment 1,565 2,122 2,154 2,182 2,142 Interest income (FTE) 106,500 105,120 100,878 99,352 99,730 Add: Current realized derivative gain (loss) (2,476) (2,714) (3,320) (3,875) (4,486) Adjusted interest income (FTE) $ 104,024 $ 102,406 $ 97,558 $ 95,477 $ 95,244 Average non ASC 310-30 loans $ 8,840,929 $ 8,728,514 $ 8,550,349 $ 8,531,652 $ 8,515,947 Yield (FTE) * 4.78% 4.78% 4.73% 4.72% 4.65% Adjusted yield (FTE) ** 4.67% 4.65% 4.58% 4.54% 4.44% * Calculated as interest income (FTE) divided by average loans. Annualized for partial-year periods. ** Calculated as adjusted interest income (FTE) divided by average loans. Annualized for partial-year periods. 26

Non-GAAP Measures 27 At or for the three months ended: December 31, 2017 September 30, 2017 June 30, 2017 March 31, 2017 December 31, 2016 Efficiency ratio: Total revenue - GAAP $ 117,296 $ 114,412 $ 114,215 $ 111,233 $ 112,549 Add: Tax equivalent adjustment 1,565 2,122 2,154 2,182 2,142 Total revenue (FTE) $ 118,861 $ 116,534 $ 116,369 $ 113,415 $ 114,691 Noninterest expense $ 54,868 $ 55,332 $ 54,922 $ 53,852 $ 52,537 Less: Amortization of intangible assets 426 430 538 550 839 Tangible noninterest expense $ 54,442 $ 54,902 $ 54,384 $ 53,302 $ 51,698 Efficiency ratio * 45.8% 47.1% 46.7% 47.0% 45.1% * Calculated as the ratio of tangible noninterest expense to total revenue (FTE). Tangible common equity and tangible common equity to tangible assets: Total stockholders' equity $ 1,767,873 $ 1,755,000 $ 1,732,983 $ 1,706,861 $ 1,678,638 Less: Goodwill and other intangible assets 747,971 748,397 748,828 749,366 749,916 Tangible common equity $ 1,019,902 $ 1,006,603 $ 984,155 $ 957,495 $ 928,722 Total assets $ 11,806,581 $ 11,690,011 $ 11,466,184 $ 11,356,841 $ 11,422,617 Less: Goodwill and other intangible assets 747,971 748,397 748,828 749,366 749,916 Tangible assets $ 11,058,610 $ 10,941,614 $ 10,717,356 $ 10,607,475 $ 10,672,701 Tangible common equity to tangible assets 9.2% 9.2% 9.2% 9.0% 8.7% Tangible book value per share: Total stockholders' equity $ 1,767,873 $ 1,755,000 $ 1,732,983 $ 1,706,861 $ 1,678,638 Less: Goodwill and other intangible assets 747,971 748,397 748,828 749,366 749,916 Tangible common equity $ 1,019,902 $ 1,006,603 $ 984,155 $ 957,495 $ 928,722 Common shares outstanding 58,896,189 58,834,066 58,761,597 58,760,517 58,755,989 Book value per share - GAAP $ 30.02 $ 29.83 $ 29.49 $ 29.05 $ 28.57 Tangible book value per share $ 17.32 $ 17.11 $ 16.75 $ 16.29 $ 15.81

Appendix 2 Agriculture Lending & Economy

Ag Lending 101 • Underwriting identical to comparable C&I and CRE loans where cash flow is the primary repayment source and loan and line amounts subject to loan value ("LTV") limits and "normalized" collateral values • Liquid markets typically exist for ag-related collateral which is the secondary repayment source (e.g., harvested grain or grain inventory, cattle, farm equipment and land sale/lease) in foreclosure scenarios • Many market and economic conditions can influence the profitability of individual borrowers; key to partner with seasoned producers that manage their own cost structure diligently Overview Grains • 30% of the Ag loan portfolio or approx. 7% of overall loan portfolio • Most borrowers in footprint in MW states (IA, SD, NE) ◦ Corn and soybeans primary crop production • Corn and soybean prices spiked beginning in late 2007 and remained high for 3-4 years ◦ Drove cost of production higher as land and other input costs were in high demand; ◦ Gross value of corn production per acre increased 138% from 2006 to 2011 (USDA) • Crop prices have reverted to more sustainable long-term levels but costs have not reset as quickly • Federally-subsidized crop insurance protects a portion of grain producers' projected revenue each year 29

Ag Lending 101 (cont'd) 30 Beef Cattle Dairy • 22.9% of the Ag loan portfolio or approx. 5% overall, primarily in SD • Beef cattle producers include: ◦ Cow-calf operators that breed cattle and raise calves to a certain weight (typically 500-600 lbs.; "Feeder Cattle") ◦ Feedlots who purchase feeder cattle and finish them for sale to processors (typically 1200+lbs.; "Live Cattle") ◦ GWB portfolio split roughly 72/28 as of 12/31/17 • Industry is very cyclical driven by supply and demand (e.g., prices paid by feedlots dictate how many calves are bred and which stock cattle are retained for breeding vs. slaughtered) • 25.8% of the Ag loan portfolio or approx. 6% overall, primarily in AZ • Very cyclical pricing over time; producers that manage costs, are vertically integrated and use risk management techniques are best suited to generate profitability over time • Arizona has a milk quota system that enhances milk price margins for units of production providing some stability for producers • Dairy (and beef cattle) producers benefit from low grain prices (primary production cost in food form for animals)

Ag Economy 31 Highlights • Industry balance sheets remain strong with debt/asset and debt/equity ratios below long-term averages and significantly below 1980s levels that precipitated, and resulted, from the period of high losses in the early 1980s • Ag sector net charge-offs have historically been low for the industry and for Great Western Bank Farm Balance Sheet Overview (1) Source: USDA Economic Research Service; 2017 is forecast data

Appendix 3 MSA Highlights

Des Moines / West Des Moines: • Iowa state capital • Insurance and financial services hub; major employers include Principal Financial, Nationwide, Wells Fargo Home Mortgage, Meredith Corp. and Ruan Transport Davenport / Moline / Rock Island (Quad Cities): • Significant advanced manufacturing, logistics, defense and food processing presence • Major employers include Deere & Co., Rock Island Arsenal, HyVee and two major health systems Cedar Rapids: • Along with Iowa City (20 miles away) comprises an economic area called the "Creative Corridor" • Significant innovative production, technology and life sciences presence • Major employers include Rockwell Collins, Transamerica and Nordstrom Direct Waterloo / Cedar Falls: • Cedar Falls is home to the University of Northern Iowa • Advanced manufacturing hub; major employers include Deere & Co., health systems and UNI Sioux City: • Marked by strong business climate and very low unemployment; situated on the Iowa / Nebraska / South Dakota border at the navigational head of the Missouri River Iowa City: • Home of the University of Iowa and U of I Hospitals and Clinics which employ over 33,000 people; major hub for arts and culture Ames: • Home to Iowa State University, which boasts cutting edge programs in agricultural science and bio-economics 33Areas shaded green are Metropolitan Statistical Areas (darker) and Micropolitan Statistical Areas (lighter) where GWB has a branch or LPO presence Iowa MSAs 1.9 million aggregate 7 MSA population

Nebraska MSAs Omaha/ Council Bluffs: • MSA population of nearly 1 million • Headquarters to four Fortune 500 companies including Berkshire Hathaway, Union Pacific, Mutual of Omaha and Peter Kiewit & Sons • Home of Creighton University, University of Nebraska- Omaha and University of Nebraska Medical Center Lincoln: • Nebraska state capital • Home of the University of Nebraska • Insurance and financial services hub with key employers including Assurity Life, Ameritas and State Farm • Other robust private sector employers in transportation, manufacturing and start-up tech firms Grand Island: • Part of the "Tri-Cities" of Central Nebraska along with Hastings and Kearney - bringing the total trade area population to nearly 150,000 • Strong agricultural and manufacturing presence Areas shaded green are Metropolitan Statistical Areas (darker) and Micropolitan Statistical Areas (lighter) where GWB has a branch or LPO presence 34 1.3 million aggregate 3 MSA population

South Dakota MSAs Sioux Falls: • Largest South Dakota MSA has experienced rapid growth in recent years • Hub for regional health care with two major health systems including Sanford Health, which has received considerable philanthropic support, and Avera Health • Strong banking and finance presence including the home of corporate charters for Wells Fargo and Citi Rapid City: • Gateway to prime South Dakota tourism industry including the Black Hills, Mt. Rushmore, the Badlands, Deadwood (historical and casinos) and the annual Sturgis motorcycle rally • Federal government is a major employer between six national parks in close proximity and Ellsworth Air Force Base Areas shaded green are Metropolitan Statistical Areas (darker) and Micropolitan Statistical Areas (lighter) where GWB has a branch or LPO presence 35 400,000 aggregate 2 MSA population

Colorado MSAs Denver / Aurora / Lakewood: • 19th largest MSA with population approaching 3 million • All four major pro sports represented with franchises • Significant recent population growth supported by inflow of many new employers especially in the technology sector Colorado Springs: • Major military presence including USAF Academy, Ft. Carson and Peterson and Shriever AFBs • Strong employment by defense and cybersecurity contractors • Home of US Olympic Committee and related entities Fort Collins: • Home of Colorado State University • Large employers in both manufacturing and technology • Hub for the micro-brewery industry Boulder: • Home of the University of Colorado, known for science, engineering and research • Highest concentration of tech startups anywhere in the country Greeley: • Home of the University of Northern Colorado • Diverse economic footprint including industry, agriculture and energy Areas shaded green are Metropolitan Statistical Areas (darker) and Micropolitan Statistical Areas (lighter) where GWB has a branch or LPO presence 36 4.5 million aggregate 5 MSA population

Other States Phoenix / Mesa / Scottsdale: • 12th largest MSA with population over 4.5 million • Home of Arizona State University • GWB opened a Scottsdale office in 2016 • Large dairy lending concentration in suburban Phoenix Tucson: • Home of University of Arizona • Major defense contractor and military presence Areas shaded green are Metropolitan Statistical Areas (darker) and Micropolitan Statistical Areas (lighter) where GWB has a branch or LPO presence Kansas City: • 27th largest MSA with population over 2 million • Two major professional sports franchises • New Power and Light District is a booming sports and entertainment complex • Diverse economic activity including Sprint Nextel's world headquarters Minneapolis / St. Paul / Bloomington: • 16th largest MSA with population over 3.5 million • Home of the University of Minnesota • GWB gained presence through HF Financial acquisition Fargo: • Home of North Dakota State University • Regional health care hub with healthcare industry being the largest cumulative employer 37

Appendix 4 Accounting for Loans at FV and Related Derivatives

Loans at FV and Related Derivatives 39 Overview Summary • For certain loans with an original term greater than 5 years with a fixed rate to the customer, Great Western Bank (“GWB”) has entered into equal and offsetting fixed-to-floating interest rate swaps with two US counterparties • Total size of the portfolio was $980.1 million at December 31, 2017 • GWB has elected the Fair Value Option (ASC 825) on these loans and applies a similar treatment to the related derivatives: • Changes in the fair value of the loans and the derivatives and the current period realized cost (benefit) of the derivatives (i.e., the net pay fixed/receive floating settlement) are recorded in earnings through noninterest income • This differs significantly from most peers who have elected Hedge Accounting treatment • The historical election is irrevocable so the concept will be present for the foreseeable future in GWB’s financial statements even if different accounting elections are made on future originations • Management presents non-GAAP measures to provide more clarity on the underlying economics Income Statement Line Item: Net increase (decrease) in fair value of loans at fair value Net realized and unrealized gain (loss) on derivatives Net Relationship Notes Increase (decrease) in FV related to interest rates $ (9,703) $ 9,703 $ — (1) Increase (decrease) in FV related to credit $ 1,038 $ — $ 1,038 (2) Current period realized cost of derivatives $ — $ (2,476) $ (2,476) (3) Subtotal, loans at FV and related derivatives $ (8,665) $ 7,227 $ (1,438) (4) (1) Equal and offsetting each period. Changes in the FV of each financial asset and liability driven by current compared to contractual rates. (2) Management records an adjustment for credit risk in noninterest income based on loss history for similar loans, adjusted for an assessment of existing market conditions for each loan segment. The FV adjustment related to credit is not included in the ALLL but loans are included in the ALLL coverage ratio denominator. (3) Current period actual cost of fixed-to-float interest rate swaps. Within non-GAAP financial measures, management reclassifies this component to interest income, resulting in adjusted interest income, adjusted net interest income and adjusted NIM, reflecting the underlying economics of the transactions. All else equal, this drag on earnings will reduce as short-term LIBOR rates increase. (4) While US GAAP mandates the presentation of these items in noninterest income, management believes the residual net amount economically represents the net credit exposure of this segment of the portfolio - presented as a "credit-related charge" in the earnings release and elsewhere (see note (2)) - and the current period derivative cost which should be analyzed relative to gross interest income received from the loan customers (see note (3)) as presented in non-GAAP measures.