Exhibit 99.1 Spirit of Texas Bancshares, Inc. Stephens Texas Bank Field Trip 2021 February 3, 2021 1 SPIRIT SPIRIT OF OF TEXAS TEXASExhibit 99.1 Spirit of Texas Bancshares, Inc. Stephens Texas Bank Field Trip 2021 February 3, 2021 1 SPIRIT SPIRIT OF OF TEXAS TEXAS

Important Information ABOUT SPIRIT OF TEXAS BANCSHARES, INC. Spirit of Texas Bancshares, Inc. (“Spirit,” “STXB,” “Company,” “we,” “our” or “us”), through its  wholly‐owned subsidiary, Spirit of Texas Bank (the “Bank”), provides a wide range of relationship‐driven commercial banking  products and services tailored to meet the needs of businesses, professionals and individuals. Spirit of Texas Bank has 36 locations in the  Houston, Dallas/Fort Worth, Bryan/College Station, San Antonio‐New Braunfels,  Austin, Tyler and Corpus Christi metropolitan areas, as well as in North Central and North East Texas. Please visit www.sotb.com for more information. Our website is an inactive textual reference only. FORWARD‐LOOKING STATEMENTS This presentation contains, and future oral and written statements of the Company and its management may contain, forward‐looking statements  within the meaning of the Private Securities Litigation Reform Act of  1995 that are subject to risks and uncertainties and are made pursuant to the safe harbor provisions of Section 27A of the Securities  Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as  amended. Any statements about our expectations, beliefs, plans, predictions, protections, forecasts, objectives, assumptions or future events or performance are not historical facts and may be forward‐ looking. Forward‐looking statements are typically, but not exclusively, identified by the use of forward‐looking terminology such as “believes,”  “expects,” “could,” “may,” “will, “should,” “seeks,” “likely,” “intends”  “plans,” “pro forma,” “projects,” “estimates” or “anticipates” or the negative of these words and phrases or  similar words or phrases that are predictions of or indicate future events or trends and that do not relate  solely to historical matters. You can also identify forward‐looking statements by discussions of strategy, plans or intentions. Forward‐looking statements involve numerous risks and uncertainties and you should not rely  on them as predictions of future events. The following factors, among others, could cause actual results and future events to differ materially from those set forth or contemplated  in the forward‐looking statements: the  impact of the COVID‐19 pandemic on our business, including the impact of actions taken by governmental and regulatory authorities in  response to such pandemic, such as the Coronavirus Aid, Relief, and Economic  Security Act and the programs established thereunder, and the Bank’s participation in such programs; business and economic conditions generally  and in the bank and non‐bank financial services industries, nationally  and within our local market areas; our ability to mitigate our risk exposures; our ability to maintain our historical earnings trends;  risks related to the integration of acquired businesses and any future acquisitions; the  inability to realize expected cost savings or achieve other anticipated benefits in connection with business combinations or other acquisitions; our  ability to successfully identify and address the risks associated with our  recent, pending and possible future acquisitions; changes in management personnel; interest rate risk; credit risk associated with our loan portfolio; deteriorating asset quality and higher loan charge‐offs; time and  effort necessary to resolve nonperforming assets; adequacy of loan loss reserves; inaccuracy of the assumptions and estimates we make in  establishing reserves for probable loan losses and other estimates and  projections; lack of liquidity; fluctuations in the fair value and liquidity of the securities we hold for sale; impairment of investment  securities, goodwill, other intangible assets or deferred tax assets; our risk management  strategies; increased competition in the bank and non‐bank financial services industries, nationally, regionally or locally, which may adversely  affect pricing and terms; the accuracy of our financial statements and  related disclosures and those of companies we acquire; material weaknesses in our internal control over financial reporting; system failures or  failures to prevent breaches of our network security; other economic,  competitive, governmental, or technological factors affecting our operation, markets, products, services, and prices; the institution and outcome of  litigation and other legal proceedings against us or to which we  become subject; unanticipated regulatory or judicial proceedings and liabilities and other costs; changes in any applicable law, rule, regulation,  policy, guideline, or practice governing or affecting bank holding  companies and their subsidiaries, or with respect to tax or accounting principles, securities or otherwise, and their application by our  regulators; governmental monetary and fiscal policies; increases in our capital  requirements; and other risks identified in Spirit’s Annual Report on Form 10‐K for the year ended December 31, 2019, filed with  the Securities and Exchange Commission (“SEC”) on March 16, 2020, its Quarterly Reports  on Form 10‐Q, its Current Reports on form 8‐K and its other filings with the SEC. While forward‐looking statements reflect our good‐faith beliefs, they are not guarantees of future performance. All forward‐looking statements are necessarily only estimates of future results. Accordingly, actual  results may differ materially from those expressed in or contemplated by the particular forward‐looking statement, and, therefore, you are  cautioned not to place undue reliance on such statements. Further, any  forward‐looking statement speaks only as of the date on which it is made, and we undertake 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 or circumstances, except as required by applicable law. 2 SPIRIT SPIRIT OF OF T TEXAS EXASImportant Information ABOUT SPIRIT OF TEXAS BANCSHARES, INC. Spirit of Texas Bancshares, Inc. (“Spirit,” “STXB,” “Company,” “we,” “our” or “us”), through its wholly‐owned subsidiary, Spirit of Texas Bank (the “Bank”), provides a wide range of relationship‐driven commercial banking products and services tailored to meet the needs of businesses, professionals and individuals. Spirit of Texas Bank has 36 locations in the Houston, Dallas/Fort Worth, Bryan/College Station, San Antonio‐New Braunfels, Austin, Tyler and Corpus Christi metropolitan areas, as well as in North Central and North East Texas. Please visit www.sotb.com for more information. Our website is an inactive textual reference only. FORWARD‐LOOKING STATEMENTS This presentation contains, and future oral and written statements of the Company and its management may contain, forward‐looking statements within the meaning of the Private Securities Litigation Reform Act of 1995 that are subject to risks and uncertainties and are made pursuant to the safe harbor provisions of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. Any statements about our expectations, beliefs, plans, predictions, protections, forecasts, objectives, assumptions or future events or performance are not historical facts and may be forward‐ looking. Forward‐looking statements are typically, but not exclusively, identified by the use of forward‐looking terminology such as “believes,” “expects,” “could,” “may,” “will, “should,” “seeks,” “likely,” “intends” “plans,” “pro forma,” “projects,” “estimates” or “anticipates” or the negative of these words and phrases or similar words or phrases that are predictions of or indicate future events or trends and that do not relate solely to historical matters. You can also identify forward‐looking statements by discussions of strategy, plans or intentions. Forward‐looking statements involve numerous risks and uncertainties and you should not rely on them as predictions of future events. The following factors, among others, could cause actual results and future events to differ materially from those set forth or contemplated in the forward‐looking statements: the impact of the COVID‐19 pandemic on our business, including the impact of actions taken by governmental and regulatory authorities in response to such pandemic, such as the Coronavirus Aid, Relief, and Economic Security Act and the programs established thereunder, and the Bank’s participation in such programs; business and economic conditions generally and in the bank and non‐bank financial services industries, nationally and within our local market areas; our ability to mitigate our risk exposures; our ability to maintain our historical earnings trends; risks related to the integration of acquired businesses and any future acquisitions; the inability to realize expected cost savings or achieve other anticipated benefits in connection with business combinations or other acquisitions; our ability to successfully identify and address the risks associated with our recent, pending and possible future acquisitions; changes in management personnel; interest rate risk; credit risk associated with our loan portfolio; deteriorating asset quality and higher loan charge‐offs; time and effort necessary to resolve nonperforming assets; adequacy of loan loss reserves; inaccuracy of the assumptions and estimates we make in establishing reserves for probable loan losses and other estimates and projections; lack of liquidity; fluctuations in the fair value and liquidity of the securities we hold for sale; impairment of investment securities, goodwill, other intangible assets or deferred tax assets; our risk management strategies; increased competition in the bank and non‐bank financial services industries, nationally, regionally or locally, which may adversely affect pricing and terms; the accuracy of our financial statements and related disclosures and those of companies we acquire; material weaknesses in our internal control over financial reporting; system failures or failures to prevent breaches of our network security; other economic, competitive, governmental, or technological factors affecting our operation, markets, products, services, and prices; the institution and outcome of litigation and other legal proceedings against us or to which we become subject; unanticipated regulatory or judicial proceedings and liabilities and other costs; changes in any applicable law, rule, regulation, policy, guideline, or practice governing or affecting bank holding companies and their subsidiaries, or with respect to tax or accounting principles, securities or otherwise, and their application by our regulators; governmental monetary and fiscal policies; increases in our capital requirements; and other risks identified in Spirit’s Annual Report on Form 10‐K for the year ended December 31, 2019, filed with the Securities and Exchange Commission (“SEC”) on March 16, 2020, its Quarterly Reports on Form 10‐Q, its Current Reports on form 8‐K and its other filings with the SEC. While forward‐looking statements reflect our good‐faith beliefs, they are not guarantees of future performance. All forward‐looking statements are necessarily only estimates of future results. Accordingly, actual results may differ materially from those expressed in or contemplated by the particular forward‐looking statement, and, therefore, you are cautioned not to place undue reliance on such statements. Further, any forward‐looking statement speaks only as of the date on which it is made, and we undertake 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 or circumstances, except as required by applicable law. 2 SPIRIT SPIRIT OF OF T TEXAS EXAS

Experienced Executive Leadership Dean O. Bass David M. McGuire Chairman and Chief Executive Officer President, Director and Chief Lending Officer • Founded the Company in 2008 • Over 39 years of banking experience • Over 46 years of banking experience • Co-Founder, President and Chief Lending Officer of Royal Oaks Bank • Founder, President and Chief Executive Officer of Royal Oaks Bank • Former Chief Executive Officer of Sterling Bank’s Fort Bend office • Former National Bank Examiner for the Office of the Comptroller of the Currency • Former Director of the Texas Bankers Association Jerry D. Golemon Allison S. Johnson Executive Vice President and Chief Operating Officer Chief Financial Officer and Chief Accounting Officer • Over 40 years of banking experience • Over 11 years of financial services experience • Former Chief Financial Officer of Bank4Texas Holdings • Former SEC Reporting Manager for Florida Community Bank • Former Chief Financial Officer, Director and Founder of Texas National Bank • Certified Public Accountant • Certified Public Accountant 3 SPIRIT SPIRIT OF OF T TEXAS EXAS Source: Company SEC filings and managementExperienced Executive Leadership Dean O. Bass David M. McGuire Chairman and Chief Executive Officer President, Director and Chief Lending Officer • Founded the Company in 2008 • Over 39 years of banking experience • Over 46 years of banking experience • Co-Founder, President and Chief Lending Officer of Royal Oaks Bank • Founder, President and Chief Executive Officer of Royal Oaks Bank • Former Chief Executive Officer of Sterling Bank’s Fort Bend office • Former National Bank Examiner for the Office of the Comptroller of the Currency • Former Director of the Texas Bankers Association Jerry D. Golemon Allison S. Johnson Executive Vice President and Chief Operating Officer Chief Financial Officer and Chief Accounting Officer • Over 40 years of banking experience • Over 11 years of financial services experience • Former Chief Financial Officer of Bank4Texas Holdings • Former SEC Reporting Manager for Florida Community Bank • Former Chief Financial Officer, Director and Founder of Texas National Bank • Certified Public Accountant • Certified Public Accountant 3 SPIRIT SPIRIT OF OF T TEXAS EXAS Source: Company SEC filings and management

Spirit of Texas Franchise Overview Footprint § Community bank founded in 2008 through the acquisition of Snook Bancshares, Inc. § Headquartered in Conroe, Texas (greater Houston SMSA) § 36 branch locations, with a presence in the greater Houston, Dallas/Fort Worth, Austin and San Antonio, Corpus Christi and Tyler markets as of 1/31/2021 § New Braunfels LPO closed on 8/31/2020 § Willow Park LPO closed on 9/16/2020 § Sale of certain assets and transfer of certain liabilities associated with the Bank’s branch located at 1010 Bay Area Boulevard, Houston, TX 77058 closed on 10/16/2020 § Millsap branch consolidation located at 107 Fannin Street, Millsap, TX 76066 closed on 11/27/2020 § Sale of certain assets and transfer of certain liabilities associated with the Bank’s branch located at 1220 N. Main Street, Jacksboro, TX 76458 closed on 1/8/2021 § Comanche National Corporation (“Comanche”) acquisition, closed on 11/14/2018, First Beeville Financial Corporation (“Beeville”) acquisition closed on 4/2/2019, and Chandler Bancorp, Inc. (“Citizens”) acquisition closed on 11/5/2019. Simmons branch acquisition closed on 2/28/2020 § Commenced paying dividends in Q3 2020 4 SPIRIT SPIRIT OF OF T TEXAS EXAS Source: STXB 4Q2020 earnings release, Company SEC filings and S&P Global Market IntelligenceSpirit of Texas Franchise Overview Footprint § Community bank founded in 2008 through the acquisition of Snook Bancshares, Inc. § Headquartered in Conroe, Texas (greater Houston SMSA) § 36 branch locations, with a presence in the greater Houston, Dallas/Fort Worth, Austin and San Antonio, Corpus Christi and Tyler markets as of 1/31/2021 § New Braunfels LPO closed on 8/31/2020 § Willow Park LPO closed on 9/16/2020 § Sale of certain assets and transfer of certain liabilities associated with the Bank’s branch located at 1010 Bay Area Boulevard, Houston, TX 77058 closed on 10/16/2020 § Millsap branch consolidation located at 107 Fannin Street, Millsap, TX 76066 closed on 11/27/2020 § Sale of certain assets and transfer of certain liabilities associated with the Bank’s branch located at 1220 N. Main Street, Jacksboro, TX 76458 closed on 1/8/2021 § Comanche National Corporation (“Comanche”) acquisition, closed on 11/14/2018, First Beeville Financial Corporation (“Beeville”) acquisition closed on 4/2/2019, and Chandler Bancorp, Inc. (“Citizens”) acquisition closed on 11/5/2019. Simmons branch acquisition closed on 2/28/2020 § Commenced paying dividends in Q3 2020 4 SPIRIT SPIRIT OF OF T TEXAS EXAS Source: STXB 4Q2020 earnings release, Company SEC filings and S&P Global Market Intelligence

STXB Acquisition History 2020: Simmons Bank Branch Deal 2020: (4 branches) PPP Loans Total Assets Since Inception ($M) 2019: $3,085 Acquisition of 37% Pro Forma CAGR 37% Pro Forma CAGR Through Through 12/31/2020 12/31/2020 Citizens $271 $2,824 (7 branches) $278 2019: $439 Acquisition of Beeville (3 branches) 2018: $437 2013: Acquisition of Acquisition of Comanche (8 branches) Peoples Bank (2 branches) 2012: 2016: Acquisition of PlainsCapital Oasis Bank Branch Deal $1,467 2013: (1 branch) Acquisition of Texas Community Bank $339 2011: (FDIC-Assisted) Texas Community $1,030 $980 2009: Bank Third Coast Bank Branch Deal $844 Initial Branch Deal (3 branches) Public $706 (2 branches) $670 Offering (May 2018) $205 2008: $463 Acquisition of $79 $322 Snook Bancshares $201 $144 $53 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 (1) Total Assets Acquired Assets 1) 2008-2014 total assets represented by bank-level regulatory financial data; 2015-2020 total assets represented by consolidated financial data; figures provided 5 SPIRIT SPIRIT OF OF T TEXAS EXAS are as of 12/31, unless otherwise specified Source: Company SEC filings and S&P Global Market IntelligenceSTXB Acquisition History 2020: Simmons Bank Branch Deal 2020: (4 branches) PPP Loans Total Assets Since Inception ($M) 2019: $3,085 Acquisition of 37% Pro Forma CAGR 37% Pro Forma CAGR Through Through 12/31/2020 12/31/2020 Citizens $271 $2,824 (7 branches) $278 2019: $439 Acquisition of Beeville (3 branches) 2018: $437 2013: Acquisition of Acquisition of Comanche (8 branches) Peoples Bank (2 branches) 2012: 2016: Acquisition of PlainsCapital Oasis Bank Branch Deal $1,467 2013: (1 branch) Acquisition of Texas Community Bank $339 2011: (FDIC-Assisted) Texas Community $1,030 $980 2009: Bank Third Coast Bank Branch Deal $844 Initial Branch Deal (3 branches) Public $706 (2 branches) $670 Offering (May 2018) $205 2008: $463 Acquisition of $79 $322 Snook Bancshares $201 $144 $53 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 (1) Total Assets Acquired Assets 1) 2008-2014 total assets represented by bank-level regulatory financial data; 2015-2020 total assets represented by consolidated financial data; figures provided 5 SPIRIT SPIRIT OF OF T TEXAS EXAS are as of 12/31, unless otherwise specified Source: Company SEC filings and S&P Global Market Intelligence

Proven Franchise Enhancement Loan to Deposit Ratio(1) Net Income and Earnings per Share(2) $1.79  Taxes & Provision ($M) $50.03 $1.40  104.0% Net Income ($M) Without 97.2% 94.9% 93.3% 91.6% PPP $1.03  EPS $18.72 86.8% $0.63  $29.42 $0.50  $8.28 $14.14 $10.81 $4.16 $6.95 $6.06 $3.23 $4.75 $9.98 $21.14 $31.31 $3.72 2016 2017 2018 2019 2020 2016 2017 2018 2019 2020 Return on Average Assets and Net Interest Margin Efficiency Ratio 4.60% 4.58% 83.4% 4.19% 77.6% 4.14% 4.09% 75.4% 68.2% 59.9% NIM 2.60% 2.00% Operating 1.74% 1.62% ROAA 1.33% 1.14% 1.11% 0.89% ROAA 0.47% 0.41% 2016 2017 2018 2019 2020 2016 2017 2018 2019 2020 Note: Figures provided are as of 12/31 unless otherwise specified Source: STXB 4Q2020 earnings release, Company SEC filings and S&P Global Market Intelligence (1) Includes $278mm in PPP loans and $23mm in PPP-related deposit accounts (2)Taxes were $1.6mm, $3.6mm, $2.0mm, $5.4mm and $7.5mm for 2016, 2017, 2018, 2019 & 2020, respectively. 6 SPIRIT SPIRIT OF OF T TEXAS EXAS Provision was $1.6mm, $2.5mm, $2.2mm, $2.9mm and $11.3mm for 2016, 2017, 2018, 2019 and 2020, respectively. (3)Operating ROAA calculated as EBIT / Average Total AssetsProven Franchise Enhancement Loan to Deposit Ratio(1) Net Income and Earnings per Share(2) $1.79 Taxes & Provision ($M) $50.03 $1.40 104.0% Net Income ($M) Without 97.2% 94.9% 93.3% 91.6% PPP $1.03 EPS $18.72 86.8% $0.63 $29.42 $0.50 $8.28 $14.14 $10.81 $4.16 $6.95 $6.06 $3.23 $4.75 $9.98 $21.14 $31.31 $3.72 2016 2017 2018 2019 2020 2016 2017 2018 2019 2020 Return on Average Assets and Net Interest Margin Efficiency Ratio 4.60% 4.58% 83.4% 4.19% 77.6% 4.14% 4.09% 75.4% 68.2% 59.9% NIM 2.60% 2.00% Operating 1.74% 1.62% ROAA 1.33% 1.14% 1.11% 0.89% ROAA 0.47% 0.41% 2016 2017 2018 2019 2020 2016 2017 2018 2019 2020 Note: Figures provided are as of 12/31 unless otherwise specified Source: STXB 4Q2020 earnings release, Company SEC filings and S&P Global Market Intelligence (1) Includes $278mm in PPP loans and $23mm in PPP-related deposit accounts (2)Taxes were $1.6mm, $3.6mm, $2.0mm, $5.4mm and $7.5mm for 2016, 2017, 2018, 2019 & 2020, respectively. 6 SPIRIT SPIRIT OF OF T TEXAS EXAS Provision was $1.6mm, $2.5mm, $2.2mm, $2.9mm and $11.3mm for 2016, 2017, 2018, 2019 and 2020, respectively. (3)Operating ROAA calculated as EBIT / Average Total Assets

Steady Balance Sheet Growth Total Assets ($000) Total Loans ($000) $2,391,675 $3,085,464 $2,384,622 PPP Loans $1,771,171 $277.8mm $1,466,753 $1,096,885 $1,030,298 $872,933 $980,489 $776,864 2016 2017 2018 2019 2020 2016 2017 2018 2019 2020 Total Deposits ($000) Total Equity ($000) $360,779 $345,705 $2,459,135 $1,928,126 $198,796 $1,182,648 $835,368 $814,438 $99,139 $92,896 2016 2017 2018 2019 2020 2016 2017 2018 2019 2020 7 SPIRIT SPIRIT OF OF T TEXAS EXAS Note: Figures provided are as of 12/31 unless otherwise specified Source: STXB 4Q2020 earnings release, Company SEC filings and S&P Global Market IntelligenceSteady Balance Sheet Growth Total Assets ($000) Total Loans ($000) $2,391,675 $3,085,464 $2,384,622 PPP Loans $1,771,171 $277.8mm $1,466,753 $1,096,885 $1,030,298 $872,933 $980,489 $776,864 2016 2017 2018 2019 2020 2016 2017 2018 2019 2020 Total Deposits ($000) Total Equity ($000) $360,779 $345,705 $2,459,135 $1,928,126 $198,796 $1,182,648 $835,368 $814,438 $99,139 $92,896 2016 2017 2018 2019 2020 2016 2017 2018 2019 2020 7 SPIRIT SPIRIT OF OF T TEXAS EXAS Note: Figures provided are as of 12/31 unless otherwise specified Source: STXB 4Q2020 earnings release, Company SEC filings and S&P Global Market Intelligence

Asset Quality Remains Stable Nonperforming Loans (1) / Loans Held for Investment Past Due Trends as a Percent of Total Loans 30-89 DPD 90 + DPD Nonaccrual Nonperforming Loans ($mm) 0.49% Nonperforming Loans / Loans HFI 0.45% 0.41% 0.49% 0.49% 0.37% 0.36% 0.41% 0.36% 0.30% 0.37% 0.31% 0.25% 0.17% 0.17% 0.03% 0.00% 0.00% 0.00% 0.00% $3.8 $3.6 $5.3 $6.5 $8.6 2016 2017 2018 2019 2020 2016 2017 2018 2019 2020 Net Charge-Offs / Average Loans (2) 0.16% 0.17% YTD Net Charge-Offs (000’s) 0.14% Net Charge-Offs / Average Loans 0.09% 0.05% $0.3 $1.2 $1.5 $2.4 $2.0 2016 2017 2018 2019 2020 Note: Figures provided are as of 12/31 unless otherwise specified Source: STXB 4Q2020 earnings release, Company SEC filings and S&P Global Market Intelligence 8 SPIRIT SPIRIT OF OF T TEXAS EXAS (1) Nonperforming Loans (NPLs) include loans in nonaccrual status. Loans on deferral due to COVID are not counted as NPLs (2) PPP loans included in totals for average loans and loans held for investmentAsset Quality Remains Stable Nonperforming Loans (1) / Loans Held for Investment Past Due Trends as a Percent of Total Loans 30-89 DPD 90 + DPD Nonaccrual Nonperforming Loans ($mm) 0.49% Nonperforming Loans / Loans HFI 0.45% 0.41% 0.49% 0.49% 0.37% 0.36% 0.41% 0.36% 0.30% 0.37% 0.31% 0.25% 0.17% 0.17% 0.03% 0.00% 0.00% 0.00% 0.00% $3.8 $3.6 $5.3 $6.5 $8.6 2016 2017 2018 2019 2020 2016 2017 2018 2019 2020 Net Charge-Offs / Average Loans (2) 0.16% 0.17% YTD Net Charge-Offs (000’s) 0.14% Net Charge-Offs / Average Loans 0.09% 0.05% $0.3 $1.2 $1.5 $2.4 $2.0 2016 2017 2018 2019 2020 Note: Figures provided are as of 12/31 unless otherwise specified Source: STXB 4Q2020 earnings release, Company SEC filings and S&P Global Market Intelligence 8 SPIRIT SPIRIT OF OF T TEXAS EXAS (1) Nonperforming Loans (NPLs) include loans in nonaccrual status. Loans on deferral due to COVID are not counted as NPLs (2) PPP loans included in totals for average loans and loans held for investment

Loan Portfolio Loan Portfolio – Total Bank Municipal Consumer 2% 1% C&I - Other Organic Acq. Since 2018 Total Bank ($000’s) ($000’s) ($000’s) 13% $530,770 $59,454 $589,655 C&I CRE - Non OO 268,518 93,840 362,928 Mortgage C&I - PPP 283,754 131,734 415,488 Const, Land & Dev 27% 177,986 120,659 298,646 CRE OO 12% 443,062 212,829 655,892 CRE Non OO 8,954 3,088 12,042 Consumer $2.39 Billion 55,050 505 55,555 Municipal $1,768,094 $622,111 $2,390,205 Total • Well diversified portfolio 15% Mortgage 13% • Average loan size $241k as of December 31, 2020 CRE - OO 17% • Limited exposure to industries directly impacted by COVID-19 (see Const, Land & Dev slide 10) 9 SPIRIT SPIRIT OF OF T TEXAS EXAS Note: Figures provided are as of 12/31/2020 unless otherwise specified Source: STXB 4Q2020 earnings release, Company SEC filings and S&P Global Market IntelligenceLoan Portfolio Loan Portfolio – Total Bank Municipal Consumer 2% 1% C&I - Other Organic Acq. Since 2018 Total Bank ($000’s) ($000’s) ($000’s) 13% $530,770 $59,454 $589,655 C&I CRE - Non OO 268,518 93,840 362,928 Mortgage C&I - PPP 283,754 131,734 415,488 Const, Land & Dev 27% 177,986 120,659 298,646 CRE OO 12% 443,062 212,829 655,892 CRE Non OO 8,954 3,088 12,042 Consumer $2.39 Billion 55,050 505 55,555 Municipal $1,768,094 $622,111 $2,390,205 Total • Well diversified portfolio 15% Mortgage 13% • Average loan size $241k as of December 31, 2020 CRE - OO 17% • Limited exposure to industries directly impacted by COVID-19 (see Const, Land & Dev slide 10) 9 SPIRIT SPIRIT OF OF T TEXAS EXAS Note: Figures provided are as of 12/31/2020 unless otherwise specified Source: STXB 4Q2020 earnings release, Company SEC filings and S&P Global Market Intelligence

At-Risk Loan Portfolio At-Risk Loans to Entire Portfolio Restaurants Hospitality Retail Strip 1.4% 3.9% Centers 7.5% At-Risk Portfolio (000’s) Oil & Gas Restaurants $33,022 Direct Hospitality 93,318 2.2% Retail Strip Centers 179,455 Oil & Gas Direct 52,999 Oil & Gas Oil & Gas Indirect 27,292 Indirect Remainder of Portfolio 2,004,119 1.1% Total $2,390,205 Remainder of • Total at-risk exposure is 16.2% of the total Portfolio loan portfolio 83.8% 10 SPIRIT SPIRIT OF OF T TEXAS EXAS Note: Figures provided are as of 12/31/2020 Source: STXB 4Q2020 earnings release and S&P Global Market IntelligenceAt-Risk Loan Portfolio At-Risk Loans to Entire Portfolio Restaurants Hospitality Retail Strip 1.4% 3.9% Centers 7.5% At-Risk Portfolio (000’s) Oil & Gas Restaurants $33,022 Direct Hospitality 93,318 2.2% Retail Strip Centers 179,455 Oil & Gas Direct 52,999 Oil & Gas Oil & Gas Indirect 27,292 Indirect Remainder of Portfolio 2,004,119 1.1% Total $2,390,205 Remainder of • Total at-risk exposure is 16.2% of the total Portfolio loan portfolio 83.8% 10 SPIRIT SPIRIT OF OF T TEXAS EXAS Note: Figures provided are as of 12/31/2020 Source: STXB 4Q2020 earnings release and S&P Global Market Intelligence

Loan Deferrals Loan Deferrals as of 9/30/20 Loan Deferrals as of 12/31/20 Restaurants Restaurants 2.5% 2.7% Retail Strip Hospitality Centers Hospitality 14.4% 1.6% 18.0% Retail Strip Oil & Gas Centers 19.2% Decrease Direct 11.4% 0.3% Deferrals in Q4 Remainder of Remainder of Deferred Deferred Loans Loans 71.5% 77.6% 4.6% 3.8% Deferrals / Loans HFI Deferrals / Loans HFI Loan Type Balance (000’s) % of Deferrals Loan Type Balance (000’s) % of Deferrals $                3,037 2.70% $               2,296  2.5% Restaurants Restaurants Hospitality 16,322 14.40% Hospitality 16,447  18.0% Retail Strip Centers 12,865 11.40% Retail Strip Centers 1,476  1.6% Oil & Gas Direct ‐ 0.00% Oil & Gas Direct 233  0.3% Oil & Gas Indirect ‐ 0.00% Oil & Gas Indirect ‐0.0% Remainder of Deferred Remainder of Deferred 80,757 71.50% 70,829  77.6% Loans Loans $           112,981  100.00% $            91,280  100.0% Total Total 11 SPIRIT SPIRIT OF OF T TEXAS EXAS Source: STXB 4Q2020 earnings release and Company SEC filings, and S&P Global Market IntelligenceLoan Deferrals Loan Deferrals as of 9/30/20 Loan Deferrals as of 12/31/20 Restaurants Restaurants 2.5% 2.7% Retail Strip Hospitality Centers Hospitality 14.4% 1.6% 18.0% Retail Strip Oil & Gas Centers 19.2% Decrease Direct 11.4% 0.3% Deferrals in Q4 Remainder of Remainder of Deferred Deferred Loans Loans 71.5% 77.6% 4.6% 3.8% Deferrals / Loans HFI Deferrals / Loans HFI Loan Type Balance (000’s) % of Deferrals Loan Type Balance (000’s) % of Deferrals $ 3,037 2.70% $ 2,296 2.5% Restaurants Restaurants Hospitality 16,322 14.40% Hospitality 16,447 18.0% Retail Strip Centers 12,865 11.40% Retail Strip Centers 1,476 1.6% Oil & Gas Direct ‐ 0.00% Oil & Gas Direct 233 0.3% Oil & Gas Indirect ‐ 0.00% Oil & Gas Indirect ‐0.0% Remainder of Deferred Remainder of Deferred 80,757 71.50% 70,829 77.6% Loans Loans $ 112,981 100.00% $ 91,280 100.0% Total Total 11 SPIRIT SPIRIT OF OF T TEXAS EXAS Source: STXB 4Q2020 earnings release and Company SEC filings, and S&P Global Market Intelligence

Allowance for Loan and Lease Losses Allowance by Loan Type Consumer Municipal 1.0% 0.3% CRE 31.4% $16.0 Million • A significant increase in C&D and CRE reserves during 2020 due to qualitative 0.67% Gross Coverage Ratio factor deterioration as opposed to credit C&I 1.04% quality migration 55.8% Organic Coverage Ratio(1) • Incurred loss model is expected to Const, Land & Dev 10.7% result in a gradual build up in reserves Mortgage 0.9% over the next two quarters due to Allowance / Nonperforming Loans (2) qualitative factors and then unwind as actual losses emerge and charge-offs Allowance (000’s) 186.39% occur Allowance / Nonperforming Loans 157.22% • We do not expect a material increase in 118.18% 114.45% 104.18% modeled default rates beyond those indicated by where we believe we are in the current credit cycle $4,357 $5,652 $6,286 $6,737 $16,026 2016 2016 2017 2017 2018 2018 2019 2019 2020 2020 (1) Excludes PPP loans, which are fully guaranteed and not reserved for as of 12/31/2020, and loans acquired through a business combination (2) Nonperforming Loans (NPLs) include loans in nonaccrual status. Loans on deferral due to COVID are not counted as NPLs 12 SPIRIT SPIRIT OF OF T TEXAS EXAS Note: Figures provided are as of 12/31/2020 unless otherwise specified Source: STXB 4Q2020 earnings release, Company SEC filings and S&P Global Market IntelligenceAllowance for Loan and Lease Losses Allowance by Loan Type Consumer Municipal 1.0% 0.3% CRE 31.4% $16.0 Million • A significant increase in C&D and CRE reserves during 2020 due to qualitative 0.67% Gross Coverage Ratio factor deterioration as opposed to credit C&I 1.04% quality migration 55.8% Organic Coverage Ratio(1) • Incurred loss model is expected to Const, Land & Dev 10.7% result in a gradual build up in reserves Mortgage 0.9% over the next two quarters due to Allowance / Nonperforming Loans (2) qualitative factors and then unwind as actual losses emerge and charge-offs Allowance (000’s) 186.39% occur Allowance / Nonperforming Loans 157.22% • We do not expect a material increase in 118.18% 114.45% 104.18% modeled default rates beyond those indicated by where we believe we are in the current credit cycle $4,357 $5,652 $6,286 $6,737 $16,026 2016 2016 2017 2017 2018 2018 2019 2019 2020 2020 (1) Excludes PPP loans, which are fully guaranteed and not reserved for as of 12/31/2020, and loans acquired through a business combination (2) Nonperforming Loans (NPLs) include loans in nonaccrual status. Loans on deferral due to COVID are not counted as NPLs 12 SPIRIT SPIRIT OF OF T TEXAS EXAS Note: Figures provided are as of 12/31/2020 unless otherwise specified Source: STXB 4Q2020 earnings release, Company SEC filings and S&P Global Market Intelligence

Loan Discount on Acquired Loans Fair Value Mark by Loan Type Municipal Consumer C&I 0.1% 0.7% 2.4% 1-4 Fam 19.7% • Analysis performed at December 31, 2020 indicated allowance required on CRE 41.5% the Comanche portfolio, and no other acquired portfolios $5.4 Million • Quarterly accretion contributes approximately 3% to net interest income • Unamortized discount will accrete into interest income over the next 25 months Const, Land & Dev 35.6% 13 SPIRIT SPIRIT OF OF T TEXAS EXAS Note: Figures provided are as of 12/31/2020, unless otherwise specified Source: STXB 4Q2020 unaudited financial statementsLoan Discount on Acquired Loans Fair Value Mark by Loan Type Municipal Consumer C&I 0.1% 0.7% 2.4% 1-4 Fam 19.7% • Analysis performed at December 31, 2020 indicated allowance required on CRE 41.5% the Comanche portfolio, and no other acquired portfolios $5.4 Million • Quarterly accretion contributes approximately 3% to net interest income • Unamortized discount will accrete into interest income over the next 25 months Const, Land & Dev 35.6% 13 SPIRIT SPIRIT OF OF T TEXAS EXAS Note: Figures provided are as of 12/31/2020, unless otherwise specified Source: STXB 4Q2020 unaudited financial statements

Payroll Protection Program (PPP) • Approved and funded $428.0 million in 3,321 loans as of December 31, 2020 under the CARES Act • As of December 31, 2020, total PPP fee income recognized was $6.8 million, net of deferred costs • As of December 31, 2020, $146.9 million of PPP loans have received full forgiveness • Remaining PPP fee income to be recognized, net of deferred costs is $3.3 million 14 SPIRIT SPIRIT OF OF T TEXAS EXAS Note: Figures provided are as of 12/31/2020, unless otherwise specified Source: STXB 4Q2020 unaudited financial statementsPayroll Protection Program (PPP) • Approved and funded $428.0 million in 3,321 loans as of December 31, 2020 under the CARES Act • As of December 31, 2020, total PPP fee income recognized was $6.8 million, net of deferred costs • As of December 31, 2020, $146.9 million of PPP loans have received full forgiveness • Remaining PPP fee income to be recognized, net of deferred costs is $3.3 million 14 SPIRIT SPIRIT OF OF T TEXAS EXAS Note: Figures provided are as of 12/31/2020, unless otherwise specified Source: STXB 4Q2020 unaudited financial statements