2017 Second Quarter                     Earnings Presentation NASDAQ: OKSB                July 26, 2017

Forward Looking Statements We 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.

Second Quarter 2017 Highlights      Net income was $5.8 million, or $0.31 per diluted share, compared to $5.3       million, or $0.28 per diluted share, in the first quarter of 2017.      Total loans stood at $1.97 billion as of June 30, 2017 and includes $114.4       million in new loan commitments in the second quarter, with $43.4 million      funded.     The quarterly net interest margin was 3.53% at June 30, 2017 compared to      3.43% at March 31, 2017 and 3.48% at June 30, 2016.      Pre-tax, pre-provision income was $10.8 million for the second quarter of 2017,      an increase of 15.1% from $9.4 million in linked quarters and an increase of      34.0% from $8.0 million in the second quarter of 2017.      Efficiency ratio improved to 57.8% for the second quarter of 2017, compared to      61.5%, adjusted for non-core expenses, for the first quarter of 2017, and      65.7% for the second quarter of 2016.      Our Board approved a cash dividend of $0.08 per share payable on August 18,      2017 to shareholders of record on August 4, 2017.     Our capital ratios all remain strong and well above the criteria for regulatory      classification as “well-capitalized”.

Credit Quality Highlights Second Quarter  2017     Potential problem loans decreased from $42.1 million to $28.7 million,      or 1.5% of total portfolio loans, a fifth consecutive quarter of      improvement.     Nonperforming loans increased $6.5 million during the second quarter      to $23.1 million as of June 30, 3017. (A payoff following quarter end      reduced NPLs to $20.6 million.)     NPAs plus PPLs have reduced from $88.8 million at 6/30/16 to $51.8      million at 6/30/17, or a 42% improvement.     There was no Other Real Estate as of June 30, 2017.     Loan growth and reserves on impaired loans led to a provision for loan      losses in the amount of $1.7 million. Our reserve position stood at      $27.3 million at June 30, 2017, which represents 1.39% of portfolio      loans.     Net charge-offs for the quarter were $2.0 million.

Energy Highlights Second Quarter 2017     Total direct energy exposure at 6/30/17 included $117.3 million in      commitments and $83.6 million in funded debt, compared to $115.0 million      in commitments and $78.8 million in funded debt at 3/31/17.     Energy exposure represents 4.2% of our total funded credit portfolio, up      slightly from 4.1% in the first quarter.      The portfolio is advanced 78% to reserve-based credits and 22% to      services based.     Including the specific allocation, the ALLL for energy credits is 3.7% a      slight increase compared to 3.6% in the first quarter.     The services portfolio has $18.8 million funded with five credits having      commitments in excess of $1 million.      86% 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.     28% of the total portfolio is criticized, down from 31% at 3/31/2017.

Healthcare Highlights – Second Quarter  2017     Core market comprised of established                             Healthcare Portfolio    healthcare providers     Additional expertise in the funding                   Total Portfolio: $429.5 million    challenges of smaller, growing healthcare     businesses    Core market expansion due to successful     entry of markets for senior housing     developers, multi-site facility operators, and     healthcare related service companies    Constantly evaluating new target niches     based upon industry evolution and the     impact of the ACA    $522 million in committed healthcare related     credit, or 22.4% of total credit commitments    $430 million in funded healthcare related     credit, or 22.0% of total funded credit     portfolio    Potential problem healthcare loans represent     only 1.6% of the funded healthcare portfolio 

       Financial Highlights                                                              2014 FY          2015 FY           2016 FY         2016 FQ2          2016 FQ3         2016 FQ4          2017 FQ1         2017 FQ2 ($ in thousands except per share data)                        12/31/14         12/31/15          12/31/16          6/30/16          9/30/16          12/31/16          3/31/17           6/30/17 Balance Sheet   Total Assets                                               1,942,034        2,357,022         2,475,392        2,402,262        2,468,042         2,475,392        2,522,594         2,572,935   Total Gross Loans                                          1,399,991        1,779,428         1,877,132        1,821,377        1,880,112         1,877,132        1,936,443         1,971,634   Total Deposits                                             1,533,999        1,884,105         1,946,018        1,902,865        1,947,924         1,946,018        1,977,265         2,013,834   Total Equity                                                  270,786          296,098           286,629          282,360          283,820           286,629          290,914           295,546 Profitability (%)   Net Income ($000)                                              21,030           17,407            17,704             5,412            4,255             6,168            5,279             5,818   ROAA                                                               1.09             0.84              0.74             0.91             0.70              1.00             0.86              0.92   ROAE                                                               7.82             6.23              6.18             7.67             5.97              8.59             7.40              7.93   Net Interest Margin                                                3.45             3.35              3.46             3.48             3.42              3.40             3.43              3.53   Efficiency Ratio                                                 72.51            70.98             65.88            65.70            66.09             64.34            63.30             57.77 Balance Sheet Ratios / Capital (%)   Loans / Deposits                                                 91.26            94.44             96.46            95.72            96.52             96.46            97.94             97.90   Tangible Common Equity / Tang Assets  (1)(3)                     13.87            11.95             11.01            11.16            10.92             11.01            10.98             10.95   Common Equity Tier 1 Capital Ratio                                 NA             13.21             12.36            12.22            11.95             12.36            12.20             12.26   Tier 1 Risk Based Capital Ratio                                  19.70            15.53             14.40            14.28            13.95             14.40            14.19             14.23   Total Risk Based Capital Ratio                                   20.96            16.79             15.66            15.53            15.21             15.66            15.44             15.48   Tier 1 Leverage Ratio                                            16.45            14.41             13.02            13.18            13.07             13.02            12.98             12.95 Asset Quality (%)        (2)   NPLs / Portfolio Loans                                             0.67             1.15              0.89             1.23             1.31              0.89             0.86              1.17   NCOs / Avg Portfolio Loans                                         0.12            (0.08)             0.18             0.07             0.03             (0.09)            0.38              0.40   Reserves / Portfolio Loans                                         2.03             1.47              1.47             1.48             1.52              1.47             1.43              1.39   Reserves / NPLs                                                302.26           128.23            165.84           120.39           116.02            165.84           166.01            118.46 Per Share Data   Tangible Book Value Per Share                                    14.02            13.98             14.50            14.20            14.33             14.50            14.72             14.98   Earnings Per Diluted Share                                         1.06             0.90              0.92             0.28             0.23              0.33             0.28              0.31  (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.

 Earnings Results                                                            Earnings Summary                                                                                                                         Q2 '17 vs.                                                                            Three Months Ended                              Q1 '17              ($ in thousands except per share data)               6/30/17           3/31/17           6/30/16            % Change             Net interest income                                 $ 21,370          $ 20,163           $ 19,695                  6.0%             Provision for loan losses                                1,729             1,776                 10                 (2.6)%               Noninterest income                                     4,521             4,880             3,871                  (7.4)%               Nontinterest expense                                 15,155            15,303            15,268                   (1.0)%             Income before taxes                                      9,007             7,964             8,288                 13.1 %                 Taxes on income                                      3,189             2,685             2,876                 18.8 %             Net income                                          $   5,818         $   5,279          $   5,412                 10.2 %             Pre-tax, pre-provision  (1)                         $ 10,766          $   9,352          $   8,035                15.1%             Diluted earnings per share                          $     0.31        $     0.28         $     0.28 This is a non-GAAP based financial measure.  See Appendix for reconciliation to the most directly comparable GAAP based measure.

Loan Portfolio                                              Owner                                            Occupied CRE                                                                                Kansas                       Commercial &           $289.2                                                                                    $141.8                          Industrial            15%                                                                                      7%                           $554.1                                                                                      Texas                            28%                                                                                        $636.7                                                                                                                        32%                                                Non-Owner                                                Occupied CRE Construction &                                    $671.9                                                                                 Oklahoma Development                                       34%                                                                                    $1,112.6    $182.6                      Residential                                                                                                 57%                                Real Estate      9%                                  $255.6                         6/30/2017                         Colorado  Consumer                         13%                                                               $80.6    $18.3                                                        $1.97 billion                        4%      1%                           Loans by Type                                                                                 Loans by Segment                                                                                                                                         Kansas                                              Owner                                                                                                                                          $158.1                                           Occupied CRE                                                                                                                                           9%                      Commercial &            $306.0                        Industrial             17%                                                                         Texas                          $558.5                                                                                          $577.3                           31%                                                                                              32%                                               Non-Owner                                               Occupied CRE                                                                                                                                            Oklahoma                                                  $556.3                                                   30%                                                                                      $1,038.9 Construction &                                                                                                                                 57%                                                                                                    Colorado Development                    Residential     $175.8                      Real Estate                      6/30/2016                           $47.1                                                                                                       2%     10%                          $204.0                         $1.82 billion         Consumer                   11%           $20.8             1%                                                                                                Dollars in millions unless otherwise noted.

                         Nonperforming Loans                                                                                       Kansas                 Healthcare C&I                               Owner                                                                                                                                                   $0.1                      $1.5                                 Occupied CRE                                                                                                                                                   0%                       7%                                      $0.1                                                                1%                                                 Non-Owner                          Energy C&I             Occupied CRE                            $5.6                    $6.6                            24%                     28%                                                                    Texas                                                                                                                           $10.0               Oklahoma                                                                                                                           44%                                                                                                                                                 $12.9                                                                                                                                                  56%                                                     Residential                                Commercial &                                Consumer                                 Industrial          Real Estate              $0.1                                   $5.7                 $2.8                  0%                                                        12%                                   25% 6/30/2017                                                            Construction &                                                                       Development $23.1 million                                                             $0.6                                                                           3%                                    By Type                                                                           By Geographic Location                                                                       Owner                                                                    Occupied CRE                                                                             Kansas                                                                        $0.9                                                                                  $0.5                                                                         4%                                                                                   2%                                                 Non-Owner                                                                                                                                Other                           Healthcare C&I       Occupied CRE                                                                                                                                $3.8          Oklahoma                                $5.8                 $3.0                                                                       17%              $5.4                                26%                  14%                                                                                                                                                 24%                                                       Residential                                                        Real Estate                                                           $3.1                                                                          Consumer                                         Texas                                                           14%                           Energy C&I                                        $0.1                                           $7.0            Arizona                               $5.4                                           0%                                            32%               $5.6                               24%                                            Commercial &                                                                                      25%                                                                      Construction &  6/30/2016                                     Industrial               Development                                                 $2.6                                                                           $1.4 $22.3 million                                    12%                        6%                                                                          Dollars in millions unless otherwise noted.                                                   10                                                              Nonperforming loans include non-accruals and 90 days past due loans.

Loan Loss Reserve to NPL+PPL                                                                                                                                           52.78%                                                                                                                      46.94%                                                                                                 45.43%             43.90%                                                                            40.65%                                                       31.00%                                  29.94%            12/31/15              3/31/16              6/30/16             9/30/16              12/31/16             3/31/17              6/30/17 Nonperforming loans include non-accruals and 90 days past due loans. PPL is defined as potential problem loans.

Credit Risk Profile      ($000s)     $120,000                                                                                                                                          5.0%     $100,000                                                                                                                                                       4.0%      $80,000                                                                                                                                                       3.0%      $60,000                                                                                                                                                       2.0%      $40,000                                                                                                                                                       1.0%      $20,000            $-                                                                                                                                         0.0%                     2012         2013         2014         2015        2016 Q1      2016 Q2      2016 Q3       2016 Q4      2017 Q1      2017 Q2                                          NPAs                         Potential Problem Loans                          NPAs/Assets Nonperforming assets defined as nonaccrual loans, loans past due 90 days or more and still accruing, and other real estate owned.

Strong Core Deposit Franchise    $2.01 billion Total Deposits (6/30/2017)                         Deposits by Type                                                                        Cost of Deposits                                                        Interest Bearing                                                             Demand                                                              $177                    Non-interest Bearing                        9%                                                                                              0.59%                         Demand                           $557                                                                                                                    0.52%                                                                                                                                       0.48%                           27%                                                                                             0.45%                                                                                                               0.43%                                                                                                   0.40%                                                                                       0.37%          Other Time             Deposits              $219               11%                                        Money market                                            Accounts               Time Deposits                 $599              $100,000 or More                30%                    $404                     20%                                      Savings Accounts                                             $58                                              3% Dollars in millions.

NIM/Cost of Deposits ($000s) $22,000                                                                                                 5.0%                                                                                                         4.5% $21,500                                                                                                         4.0% $21,000       3.48%        3.54%        3.48%        3.42%         3.40%        3.43%        3.53%      3.5%                                                                                                         3.0% $20,500                                                                                                         2.5% $20,000                                                                                                         2.0% $19,500                                                                                                 1.5%                                                                                                         1.0%                                                                                              0.59% $19,000       0.37%        0.40%        0.43%        0.45%         0.48%        0.52%                                                                                                         0.5% $18,500                                                                                                 0.0%               Q4 '15       Q1 '16       Q2 '16       Q3 '16       Q4 '16       Q1 '17       Q2 '17                         Net Interest Income        Cost of Deposits       Net Interest Margin

Noninterest Income                                                                                                             $4,880                                                                     $4,555                                                     $4,521          $4,179                                                                         $4,244                                                 $3,871                             $3,415        12/31/15             3/31/16             6/30/16            9/30/16             12/31/16            3/31/17             6/30/17                 Service Charges and Fees         Gain on Sales of Loans        Gain on Investment Securities         Other Dollars in thousands.

Noninterest Expense          $17,099                             $15,996                               $16,156            $15,826                                                $15,268                                                  $15,303            $15,155         12/31/15            3/31/16            6/30/16            9/30/16           12/31/16            3/31/17            6/30/17            Salaries and Employee Benefits                 Occupancy           General and Administrative                Other Dollars in thousands.

Strong Capital Position                         Common Equity Tier 1                                                                   Tier 1 Risk-based Capital Ratio 25.0%                                                                                         25.0% 20.0%                                                                                         20.0%                                                                                                          15.3%                                                                                                                    14.1%      14.3%     14.0%      14.4%      14.2%     14.2% 15.0%     13.2%                                                                                15.0%                      12.1%     12.2%      12.0%      12.4%     12.2%      12.3%                                                                                                                                                                                  8.0% Well  10.0%                                                                              6.5% Well   10.0%                                                                                    Capitalized                                                                                   Capitalized  5.0%                                                                                           5.0%  0.0%                                                                                           0.0%          12/31/15   3/31/16    6/30/16    9/30/16   12/31/16   3/31/17   6/30/17                        12/31/15   3/31/16   6/30/16    9/30/16   12/31/16   3/31/17    6/30/17                          Tier 1 Leverage Ratio                                                                  Total Risk-Based Capital Ratio  25.0%                                                                                         25.0%  20.0%                                                                                         20.0%                                                                                                           16.6%                                                                                                                     15.4%      15.5%     15.2%      15.7%      15.4%     15.5%            14.4%  15.0%                13.5%     13.2%      13.1%     13.0%      13.0%      13.0%                15.0%                                                                                                                                                                                   10.0% Well                                                                                                                                                                                    Capitalized  10.0%                                                                                          10.0%                                                                                     5.0% Well                                                                                      Capitalized   5.0%                                                                                           5.0%   0.0%                                                                                           0.0%           12/31/15   3/31/16    6/30/16    9/30/16   12/31/16   3/31/17  6/30/2017                       12/31/15   3/31/16    6/30/16   9/30/16   12/31/16   3/31/17   6/30/2017

2017 Priorities    Successfully 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                                                                                                   $6.2                                                                                                                                                $5.8                                                       $5.4                                                               $5.3          $4.6                                                                              $4.3                                $1.9        12/31/15               3/31/16               6/30/16               9/30/16               12/31/16               3/31/17               6/30/17 Dollars in millions.

Quarterly Pre-Tax, Pre-Provision Income                                                                                                                                               $10.8                                                                                                                          $9.4                                                                              $8.4                  $8.6                                                       $8.0                                $7.5          $6.4        12/31/15               3/31/16               6/30/16               9/30/16               12/31/16               3/31/17               6/30/17 Dollars in millions.

Quarterly Net Interest Margin     3.48%          3.54%           3.48%          3.42%          3.40%          3.43%           3.53%    12/31/15        3/31/16        6/30/16        9/30/16        12/31/16        3/31/17        6/30/17

Total Loans by Segment                                                                                                                                         $63.4                   $80.6               $38.8                    $48.1                   $47.1                    $64.9                   $66.1                   $143.1                  $141.8               $150.5                  $161.0                   $158.1                  $156.7                  $144.6                                                                                                                                         $639.9                  $636.7               $580.5                  $560.4                   $577.3                  $605.7                  $636.6              $1,009.7                $1,012.4                 $1,038.9                $1,052.8                 $1,029.9                $1,153.4                 $1,112.6            12/31/15                 3/31/16                 6/30/16                  9/30/16                 12/31/16                 3/31/17                 6/30/17                                                          Oklahoma              Texas           Kansas           Colorado Dollars in millions.

Potential Problem Loans by Segment                                  $68.5                                               $2.7      $64.4                                   $3.6                    $2.7        $0.8                                    $18.8                  $17.7                  $45.5                  $44.0                  $42.1          $39.2        $2.8                                                        $2.7       $0.7        $4.0        $0.1                                                                                                                                   $3.6                        $2.0                                                                                                                            $28.7            $4.2                                                                  $21.0                  $19.8                   $16.3                               $2.7                                    $43.4                  $43.1                                                                                         $10.8            $30.2                                                                                   $21.0                  $20.1                   $22.0                  $15.8         12/31/15                3/31/16                 6/30/16                9/30/16                12/31/16                 3/31/17                6/30/17                                                     Oklahoma             Texas         Kansas           Colorado Dollars in millions.

Provision for Loan Loss                                 $4.38                                                                               $1.71                                        $1.78                  $1.73                                                         $0.01           $(0.57)                                                                                                    $(1.33)        12/31/15               3/31/16                6/30/16               9/30/16               12/31/16                3/31/17               6/30/17 Dollars in millions.

Loan Loss Reserve to Total Portfolio Loans       1.47%           1.53%            1.48%           1.52%           1.47%           1.43%            1.39%      12/31/15        3/31/16         6/30/16          9/30/16         12/31/16        3/31/17         6/30/17 Loan Loss Reserve to Nonperforming Loans                                                                          165.84%          166.01%       128.23%                        122.01%          120.39%         116.02%                                           118.46%       12/31/15         3/31/16          6/30/16         9/30/16         12/31/16          3/31/17         6/30/17

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 Share                                        12/31/2014       12/31/2015       12/31/2016        6/30/2016        9/30/2016       12/31/2016        3/31/2017        6/30/2017 Total Equity                          $    270,786     $    296,098     $    286,629     $    282,360     $    283,820     $    286,629     $    290,914     $    295,546 Less Goodwill & Core Deposits                  1,744          16,361           15,844           16,051           15,983           15,844           15,722           15,606 TCE                                   $    269,042     $    279,737     $    270,785     $    266,309     $    267,837     $    270,785     $    275,192     $    279,940 Total Assets                          $ 1,942,034      $ 2,357,022      $ 2,475,392      $ 2,402,262      $ 2,468,042      $ 2,475,392      $ 2,522,594      $ 2,572,935 Less Goodwill & Core Deposits                  1,744          16,361           15,844           16,051           15,983           15,844           15,722           15,606 TA                                    $ 1,940,290      $ 2,340,661      $ 2,459,548      $ 2,386,211      $ 2,452,059      $ 2,459,548      $ 2,506,872      $ 2,557,329 Common Equity to Assets                     13.94%           12.56%           11.58%           11.75%           11.50%           11.58%          11.53%           11.49% TCE to TA                                   13.87%           11.95%           11.01%          11.16%           10.92%           11.01%           10.98%           10.95% Shares outstanding                     19,193,059       20,006,802       18,674,727       18,750,783       18,685,385       18,674,727       18,689,022       18,686,273 Book Value per Common Share           $       14.11    $       14.80    $       15.35    $       15.06    $       15.19    $       15.35    $       15.57    $       15.82 Tangible BV per Share                 $       14.02    $       13.98    $       14.50    $       14.20    $       14.33    $       14.50    $       14.72    $       14.98                                                                    Pre-tax, Pre-provision Income                                                             12/31/2015     3/31/2016     6/30/2016     9/30/2016     12/31/2016    3/31/2017     6/30/017              Net Income                                    $      4,589    $    1,869    $    5,412   $    4,255    $      6,168    $   5,279     $   5,818              Taxes on income                                       2,577         1,015         2,876        2,236           3,682        2,685         3,189              Provision                                            (566)        4,375            10         1,713         (1,329)        1,776        1,729              Provions for unfunded                                (163)          215          (263)          146             32          (388)          30              Pre-tax, Pre-provision Income                 $      6,437    $    7,474    $    8,035   $    8,350    $      8,553    $   9,352     $ 10,766 Dollars in thousands, except per share amounts.

2017 Second Quarter                     Earnings Presentation NASDAQ: OKSB                July 26, 2017