017First QuarterEarnings PresentationApril 26, 2017NASDAQ: OKSB

Forward Looking StatementsWe make forward-looking statements in this presentation that are subject to risks and uncertainties. We intend these statements to be covered by the safe harbor provision for forward-looking statements contained in the Private Securities Litigation Reform Act of 1995.These forward-looking statements include:•Statements of Southwest's goals, intentions, and expectations;•Estimates of risks and of future costs and benefits;•Expectations regarding our future financial performance and the financial performance of our operating segments;•Expectations regarding regulatory actions;•Expectations regarding our ability to utilize tax loss benefits;•Expectations regarding our stock repurchase program;•Expectations regarding dividends;•Expectations regarding our planned merger with Simmons First National Corporation;•Assessments of loan quality, probable loan losses, and the amount and timing of loan payoffs;•Estimates of the value of assets held for sale or available for sale; and•Statements of our ability to achieve financial and other goals.These forward-looking statements are subject to significant uncertainties because they are based upon: the amount and timing of future changes in interest rates, market behavior, and other economic conditions; future laws, regulations, and accounting principles; changes in regulatory standards and examination policies, and a variety of other matters. These other matters include, among other things, the direct and indirect effects of economic conditions on interest rates, credit quality, loan demand, liquidity, and monetary and supervisory policies of banking regulators. Because of these uncertainties, the actual future results may be materially different from the results indicated by these forward-looking statements. In addition, Southwest's past growth and performance do not necessarily indicate our future results. For other factors, risks, and uncertainties that could cause actual results to differ materially from estimates and projections contained in forward-looking statements, please read the “Risk Factors” contained in Southwest’s reports to the Securities and Exchange Commission. We do not intend, or undertake no obligation, to update or revise any forward-looking statements contained in this presentation, whether as a result of differences in actual results, changes in assumptions, or changes in other factors affecting said statements, except as required by law.

Net income was $5.3 million, or $0.28 per diluted share, compared to $6.2 million, or $0.33 per diluted share, in the fourth quarter of 2016. Total loans are at $1.94 billion as of March 31, 2017 and includes $121.3 million in new loan commitments in the first quarter, with $87.7 million funded.The quarterly net interest margin was 3.43% at March 31, 2017 compared to 3.40% at December 31, 2016 and 3.54% at December 31, 2016.Pre-tax, pre-provision income was $9.4 million for the first quarter of 2017, an increase of 9.3% from $8.6 million in the fourth quarter of 2016 and an increase of 25.1% from $7.5 million in the first quarter of 2016.Efficiency ratio remained steady at 61.5%, adjusted for non-core expenses, for the first quarter of 2017, compared to 60.5%, adjusted for merger costs, for the fourth quarter of 2016, and improved from 67.5% for the first quarter of 2016. Our Board approved a cash dividend of $0.08 per share payable on May 19, 2017 to shareholders of record on May 5, 2017.Our capital ratios all remain strong and well above the criteria for regulatory classification as “well-capitalized”.First Quarter 2017 Highlights

Credit Quality Highlights First Quarter 2017Potential problem loans decreased from $44.0 million to $42.1 million, or 2.2% of total portfolio loans, a fourth consecutive quarter of improvement.Nonperforming loans remained at $16.6 million as of March 31 2017.Other real estate owned remained at $0.4 million as of March 31, 2017.Loan growth and reserves on impaired loans led to a provision for loan losses in the amount of $1.8 million, combined with net charge-offs of $1.8 million kept our reserve position steady at $27.5 million at March 31, 2017, which represents 1.43% of portfolio loans.

Energy Highlights First Quarter 2017Total direct energy exposure at 3/31/17 included $115.0 million in commitments and $78.8 million in funded debt, compared to $84.7 million in commitments and $48.6 million in funded debt at 12/31/16.Energy exposure represents 4.1% of our total funded credit portfolio up from 2.6% in the fourth quarter. The portfolio is advanced 83% to reserve-based credits and 17% to services a significant shift from 70% and 30%, respectively, in the fourth quarter.Including the specific allocation, the ALLL for energy credits is 3.6% compared to 4.8% in the fourth quarter.The services portfolio has $13.3 million funded with five credits having commitments in excess of $1 million. 78% of funded service portfolio is comprised of three credits, all of which are participations purchased from larger banks.There were no service portfolio downgrades in the quarter.

Healthcare Highlights –First Quarter 2017 Core market comprised of established healthcare providers Additional expertise in the funding challenges of smaller, growing healthcare businessesCore market expansion due to successful entry of markets for senior housing developers, multi-site facility operators, and healthcare related service companiesConstantly evaluating new target niches based upon industry evolution and the impact of the ACA$517 million in committed healthcare related credit, or 22.5% of total credit commitments$431 million in funded healthcare related credit, or 22.4% of total funded credit portfolioPotential problem healthcare loans represent only 2.3% of the funded healthcare portfolio Healthcare PortfolioTotal Portfolio: $431.6 million

Financial Highlights(1) Intangible assets defined as goodwill for purposes of these calculations.(2)NPLs defined as Non-Accrual loans + Loans 90+ Days Past Due, NPAs defined as NPLs + OREO.(3)This is a non-GAAP based financial measure. See Appendix for reconciliation to the most directly comparable GAAP based measure.2014 FY2015 FY2016 FY2016 FQ12016 FQ22016 FQ32016 FQ42017 FQ1($ in thousands except per share data)12/31/1412/31/1512/31/163/31/166/30/169/30/1612/31/163/31/17Balance SheetTotal Assets1,942,034 2,357,022 2,475,392 2,360,819 2,402,262 2,468,042 2,475,392 2,522,594 Total Gross Loans1,399,991 1,779,428 1,877,132 1,781,884 1,821,377 1,880,112 1,877,132 1,936,443 Total Deposits1,533,999 1,884,105 1,946,018 1,895,248 1,902,865 1,947,924 1,946,018 1,977,265 Total Equity270,786 296,098 286,629 285,661 282,360 283,820 286,629 290,914 Profitability (%)Net Income ($000)21,030 17,407 17,704 1,869 5,412 4,255 6,168 5,279 ROAA1.09 0.84 0.74 0.32 0.91 0.70 1.00 0.86 ROAE7.82 6.23 6.18 2.56 7.67 5.97 8.59 7.40 Net Interest Margin3.45 3.35 3.46 3.54 3.48 3.42 3.40 3.43 Efficiency Ratio72.51 70.98 65.88 67.48 65.70 66.09 64.34 63.30 Balance Sheet Ratios / Capital (%)Loans / Deposits91.26 94.44 96.46 94.02 95.72 96.52 96.46 97.94 Tangible Common Equity / Tang Assets(1)(3)13.87 11.95 11.01 11.49 11.16 10.92 11.01 10.98 Common Equity Tier 1 Capital RatioNA13.21 12.36 12.13 12.22 11.95 12.36 12.20 Tier 1 Risk Based Capital Ratio19.70 15.53 14.40 14.14 14.28 13.95 14.40 14.19 Total Risk Based Capital Ratio20.96 16.79 15.66 15.39 15.53 15.21 15.66 15.44 Tier 1 Leverage Ratio16.45 14.41 13.02 13.45 13.18 13.07 13.02 12.98 Asset Quality (%)(2)NPLs / Portfolio Loans0.67 1.15 0.89 1.25 1.23 1.31 0.89 0.86 NCOs / Avg Portfolio Loans0.12 (0.08) 0.18 0.74 0.07 0.03 (0.09) 0.38 Reserves / Portfolio Loans2.03 1.47 1.47 1.53 1.48 1.52 1.47 1.43 Reserves / NPLs302.26 128.23 165.84 122.01 120.39 116.02 165.84 166.01 Per Share DataTangible Book Value Per Share14.02 13.98 14.50 13.97 14.20 14.33 14.50 14.72 Earnings Per Diluted Share1.07 0.90 0.92 0.10 0.28 0.23 0.33 0.28

Earnings ResultsEarnings Summary(1)This is a non-GAAP based financial measure. See Appendix for reconciliation to the most directly comparable GAAP based measure. Q1 '17 vs. Q4'16 ($ in thousands except per share data)3/31/1712/31/163/31/16% ChangeNet interest income20,163$ 20,103$ 19,840$ 0.3%Provision for loan losses1,776 (1,329) 4,375 (233.6)% Noninterest income4,880 4,244 3,415 15.0% Nontinterest expense15,303 15,826 15,996 (3.3)% Income before taxes7,964 9,850 2,884 (19.1)% Taxes on income2,685 3,682 1,015 (27.1)% Net income5,279$ 6,168$ 1,869$ (14.4)% Pre-tax, pre-provision (1)9,352$ 8,553$ 7,474$ 9.3%Diluted earnings per share0.28$ 0.33$ 0.10$ Three Months Ended

Owner Occupied CRE$292.815%Non-Owner Occupied CRE$632.433%Residential Real Estate$228.912%Consumer$18.11%Construction & Development$193.910%Commercial & Industrial$570.029%Loan PortfolioDollars in millions unless otherwise noted.Loans by TypeLoans by SegmentOwner Occupied CRE$307.417%Non-Owner Occupied CRE$572.532%Residential Real Estate$182.310%Consumer$20.51%Construction & Development$156.59%Commercial & Industrial$507.029%3/31/2017$1.94 billion3/31/2016$1.78 billionKansas$143.18%Oklahoma$1,090.156%Colorado$63.43%Texas$639.933%Kansas$161.09%Oklahoma$1,012.457%Colorado$48.13%Texas$560.431%

Owner Occupied CRE$0.32%Non-Owner Occupied CRE$0.32%Residential Real Estate$2.817%Construction & Development$1.06%Commercial & Industrial$8.249%Energy C&I$3.219%Healthcare C&I$0.85%Nonperforming LoansDollars in millions unless otherwise noted.Nonperforming loans include non-accruals and 90 days past due loans.By TypeBy Geographic LocationOwner Occupied CRE$0.94%Non-Owner Occupied CRE$2.914%Residential Real Estate$3.416%Consumer$0.10%Construction & Development$1.47%Commercial & Industrial$1.67%Energy C&I $5.424%Healthcare C&I$6.529%3/31/2017$16.6 million3/31/2016$22.3 millionKansas$0.11%Oklahoma$7.344%Texas$9.054%Other$0.21%Kansas$0.52%Oklahoma$5.625%Arizona$6.128%Texas$7.433%Other$2.712%

Loan Loss Reserve to NPL+PPL43.90%29.94%31.00%40.65%45.43%46.94%12/31/153/31/166/30/169/30/1612/31/163/31/2017Nonperforming loans include non-accruals and 90 days past due loans.PPL is defined as potential problem loans.

Credit Risk ProfileNonperforming assets defined as nonaccrual loans, loans past due 90 days or more and still accruing, and other real estate owned.0.0%1.0%2.0%3.0%4.0%5.0% $- $20,000 $40,000 $60,000 $80,000 $100,000 $120,00020122013201420152016 Q12016 Q22016 Q32016 Q42017 Q1($000s)NPAsPotential Problem LoansNPAs/Assets

Strong Core Deposit Franchise$1.98 billion Total Deposits (3/31/2017)Deposits by TypeCost of Deposits0.37%0.40%0.43%0.45%0.48%0.52%12/31/153/31/166/30/169/30/1612/31/163/31/2017Non-interest Bearing Demand$541 27%Interest Bearing Demand$178 9%Money market Accounts$591 30%Savings Accounts$58 3%Time Deposits $100,000 or More$353 18%Other Time Deposits$256 13%Dollars in millions.

NIM/Cost of Deposits0.37%0.40%0.43%0.45%0.48%0.52%3.48%3.54%3.48%3.42%3.40%3.43%0.0%0.5%1.0%1.5%2.0%2.5%3.0%3.5%4.0%4.5%5.0% $19,000 $19,200 $19,400 $19,600 $19,800 $20,000 $20,200 $20,400Q4 '15Q1 '16Q2 '16Q3 '16Q4 '16Q1 '17($000s)Net Interest IncomeCost of DepositsNet Interest Margin

Noninterest Income$4,179$3,415$3,871$4,555$4,244$4,88012/31/153/31/166/30/169/30/1612/31/163/31/17Service Charges and FeesGain on Sales of LoansGain on Investment SecuritiesOtherDollars in thousands.

$17,099$15,996$15,268$16,156$15,826$15,30312/31/153/31/166/30/169/30/1612/31/163/31/17Salaries and Employee BenefitsOccupancyGeneral and AdministrativeOtherNoninterest ExpenseDollars in thousands.

Strong Capital PositionTier 1 Leverage RatioCommon Equity Tier 1Note: 3/31/15 calculated consistent with Basel III; previous figures consistent with General Risk-based Rules.Tier 1 Risk-based Capital RatioTotal Risk-Based Capital Ratio6.5% Well Capitalized8.0% Well Capitalized10.0% Well Capitalized5.0% Well Capitalized14.4%13.5%13.2%13.1%13.0%13.0%0.0%5.0%10.0%15.0%20.0%25.0%12/31/153/31/166/30/169/30/1612/31/163/31/1713.2%12.1%12.2%12.0%12.4%12.2%0.0%5.0%10.0%15.0%20.0%25.0%12/31/153/31/166/30/169/30/1612/31/163/31/1715.3%14.1%14.3%14.0%14.4%14.2%0.0%5.0%10.0%15.0%20.0%25.0%12/31/153/31/166/30/169/30/1612/31/163/31/1716.6%15.4%15.5%15.2%15.7%15.5%0.0%5.0%10.0%15.0%20.0%25.0%12/31/153/31/166/30/169/30/1612/31/163/31/17

2017 PrioritiesSuccessfully complete the proposed merger and consolidation with Simmons First National Corporation.Maintain strong credit quality along with conservative balance sheet and risk management.Continue appropriate growth in the commercial banking sector.Grow deposit base commensurate with loan growth.Focus on fee based income growth in mortgage, consumer and treasury.Assess, manage and add talent where available and appropriate throughout the organization.Drive growth in the healthcare banking segment.

ADDITIONAL FINANCIAL INFORMATION

Quarterly Net Income$4.6 $1.9 $5.4 $4.3 $6.2 $5.3 12/31/153/31/166/30/169/30/1612/31/163/31/17Dollars in millions.

Quarterly Pre-Tax, Pre-Provision Income$6.4 $7.5 $8.0 $8.4 $8.6 $9.4 12/31/153/31/166/30/169/30/1612/31/163/31/17Dollars in millions.

Quarterly Net Interest Margin3.48%3.54%3.48%3.42%3.40%3.43%12/31/153/31/166/30/169/30/1612/31/163/31/17

Total Loans by Segment$1,009.7 $1,012.4 $1,038.9 $1,052.8 $1,029.9 $1,153.4 $580.5 $560.4 $577.3 $605.7 $636.6 $639.9 $150.5 $161.0 $158.1 $156.7 $144.6 $143.1 $38.8 $48.1 $47.1 $64.9 $66.1 $63.4 $1,779$1,782$1,821$1,880$1,877$2,00012/31/153/31/166/30/169/30/1612/31/163/31/17OklahomaTexasKansasColoradoDollars in millions.

Potential Problem Loans by Segment$30.2 $43.4 $43.1 $21.0 $20.1 $22.0 $4.2 $18.8 $17.7 $21.0 $19.8 $16.3 $2.0 $3.6 $2.7 $2.7 $4.0$3.6 $2.8 $2.7 $0.8 $0.7 $0.1 $39.2$68.5$64.4$45.5$44.0$42.1-10103050709011012/31/153/31/166/30/169/30/1612/31/163/31/17OklahomaTexasKansasColoradoDollars in millions.

Provision for Loan Loss$(0.57)$4.38 $0.01 $1.71 $(1.33)$1.78 12/31/153/31/166/30/169/30/1612/31/163/31/17Dollars in millions.

Loan Loss Reserve to Total Portfolio Loans1.47%1.53%1.48%1.52%1.47%1.43%12/31/153/31/166/30/169/30/1612/31/163/31/17

Loan Loss Reserve to Nonperforming Loans128.23%122.01%120.39%116.02%165.84%166.01%12/31/153/31/166/30/169/30/1612/31/163/31/17

APPENDIX

The subsequent tables present non-GAAP reconciliations of the following calculations:–Tangible Common Equity (TCE) to Tangible Assets (TA) ratio–Tangible Book Value per Share–Pre-tax, Pre-provision Income

TCA to TA and Tangible Book Value Per ShareDollars in thousands, except per share amounts.12/31/201412/31/201512/31/20163/31/20166/30/20169/30/201612/31/20163/31/2017Total Equity270,786$ 296,098$ 286,629$ 285,661$ 282,360$ 283,820$ 286,629$ 290,914$ Less Goodwill & Core Deposits1,744 16,361 15,844 16,201 16,051 15,983 15,844 15,722 TCE269,042$ 279,737$ 270,785$ 269,460$ 266,309$ 267,837$ 270,785$ 275,192$ Total Assets1,942,034$ 2,357,022$ 2,475,392$ 2,360,819$ 2,402,262$ 2,468,042$ 2,475,392$ 2,522,594$ Less Goodwill & Core Deposits1,744 16,361 15,844 16,201 16,051 15,983 15,844 15,722 TA1,940,290$ 2,340,661$ 2,459,548$ 2,344,618$ 2,386,211$ 2,452,059$ 2,459,548$ 2,506,872$ Common Equity to Assets13.94%12.56%11.58%12.10%11.75%11.50%11.58%11.53%TCE to TA13.87%11.95%11.01%11.49%11.16%10.92%11.01%10.98%Shares outstanding19,193,059 20,006,802 18,674,727 19,285,045 18,750,783 18,685,385 18,674,727 18,689,022 Book Value per Common Share14.11$ 14.80$ 15.35$ 14.81$ 15.06$ 15.19$ 15.35$ 15.57$ Tangible BV per Share14.02$ 13.98$ 14.50$ 13.97$ 14.20$ 14.33$ 14.50$ 14.72$ 12/31/20153/31/20166/30/20169/30/201612/31/20163/31/2017Net Income4,589$ 1,869$ 5,412$ 4,255$ 6,168$ 5,279$ Taxes on income2,577 1,015 2,876 2,236 3,682 2,685 Provision(566)4,375101,713(1,329)1,776Provions for unfunded(163)215(263)14632(388)Pre-tax, Pre-provision Income6,437$ 7,474$ 8,035$ 8,350$ 8,553$ 9,352$ Pre-tax, Pre-provision Income

2017First QuarterEarnings PresentationApril 26, 2017NASDAQ: OKSB