Exhibit 99.1

FOR IMMEDIATE RELEASE

PROSPERITY BANCSHARES, INC.^®

REPORTS THIRD QUARTER

2018 EARNINGS

HOUSTON, October 24, 2018. Prosperity Bancshares, Inc.^® (NYSE: PB), the parent company of Prosperity Bank^® (collectively, “Prosperity”), reported net income for the quarter ended September 30, 2018 of $82.523 million, an increase of $14.615 million or 21.5% compared with $67.908 million for the same period in 2017. Net income per diluted common share increased 20.4% to $1.18 compared with $0.98 for the same period in 2017. Additionally, loans increased 5.8% (annualized) during the third quarter of 2018 and nonperforming assets remain low at 0.08% of third quarter average interest-earning assets.

“We are pleased to announce that Prosperity will increase its quarterly dividend for the fourth quarter of 2018 to $0.41 per share from $0.36 per share, a 13.9% increase.  Prosperity shareholders have enjoyed a 13% compounded annual growth rate in dividends from 2003-2017.  We will continue striving to build deposits, loans and other services to increase shareholder value,” said David Zalman, Prosperity’s Chairman and Chief Executive Officer.

“Economic fundamentals are strong in the communities we serve.  The low national unemployment rate, together with a GDP that is stronger than we have seen in years, has resulted in interest rate increases that may continue over the next year.  The increased interest rates have affected the rates we pay on deposits, the rates we charge on loans and the rates we earn on bonds.  We believe that the economy has provided an opportunity for the Federal Reserve to normalize rates and be ready to respond to any future economic downturn.  We expect the increased interest rates to help our bank,” continued Zalman.

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“Prosperity achieved 5.8% annualized loan growth on a linked quarter basis and a 20.4% increase in earnings per share to $1.18 compared with the third quarter 2017.  We also experienced a 5.3% increase in average noninterest-bearing deposits year over year,” added Zalman.

“Texas and Oklahoma should continue to prosper with no or low state income tax, a business friendly political climate and a tailwind from the energy sector.  Further, Texas has four out of the top ten fastest growing MSAs in the United States – those being Houston, Dallas, Austin and San Antonio,” stated Zalman.

“I would like to thank our shareholders and our associates for making this all possible,” concluded Zalman.

Results of Operations for the Three Months Ended September 30, 2018

Net income was $82.523 million⁽²⁾ for the three months ended September 30, 2018 compared with $67.908 million⁽³⁾ for the same period in 2017, an increase of $14.615 million or 21.5%. Net income per diluted common share was $1.18 for the three months ended September 30, 2018 compared with $0.98 for the same period in 2017, an increase of 20.4%. Annualized returns on average assets, average common equity and average tangible common equity for the three months ended September 30, 2018 were 1.46%, 8.30% and 16.17%⁽¹⁾, respectively.  Prosperity’s efficiency ratio (excluding credit loss provisions, net gains and losses on the sale of assets and taxes) was 43.50%⁽¹⁾ for the three months ended September 30, 2018.

Net interest income before provision for credit losses for the three months ended September 30, 2018 was $157.319 million compared with $156.147 million during the same period in 2017, an increase of $1.172 million or 0.8%. This change was primarily due to higher loan and investment yields and balances, partially offset by higher rates on interest-bearing liabilities and a decrease in loan discount accretion. Linked quarter net interest income before provision for credit losses decreased $4.484 million or 2.8% to $157.319 million compared with $161.803 million during the three months ended June 30, 2018. This change was primarily due to a decrease in loan discount accretion, lower collection on previously identified troubled assets compared with the second quarter 2018 and higher average rates on interest-bearing liabilities.

The net interest margin on a tax equivalent basis was 3.15% for the three months ended September 30, 2018 compared with 3.22% for the same period in 2017. This change was primarily due to a decrease in loan discount accretion of $4.429 million. On a linked quarter basis, the net interest margin was 3.15% compared with 3.28% for the three months ended June 30, 2018, primarily due to a decrease in loan discount accretion, lower collection on previously identified troubled assets compared with the second quarter 2018 and higher average rates on interest-bearing liabilities.

Noninterest income was $30.624 million for the three months ended September 30, 2018 compared with $28.809 million for the same period in 2017, an increase of $1.815 million or 6.3%. This increase was primarily due to an increase in trust income and other noninterest income. On a linked quarter basis, noninterest income increased $2.253 million or 7.9% to $30.624 million compared with $28.371 million during the three months ended June 30, 2018. This increase was primarily due to increases in other noninterest income, nonsufficient funds fees and trust income.

Noninterest expense was $81.760 million for the three months ended September 30, 2018 compared with $77.509 million for the same period in 2017, an increase of $4.251 million or 5.5%. This increase was primarily due to the 5% salary or pay rate increase for all associates following the enactment of the Tax Cuts and Jobs act. On a linked quarter basis, noninterest expense decreased $1.842 million or 2.2% to $81.760 million compared with $83.602 million during the three months ended June 30, 2018. This decrease was primarily due to a decrease in incentive compensation.

Results of Operations for the Nine Months Ended September 30, 2018

Net income was $238.481 million⁽⁴⁾ for the nine months ended September 30, 2018 compared with $205.027 million⁽⁵⁾ for the same period in 2017, an increase of $33.454 million or 16.3%.  Net income per diluted common share was $3.42 for the nine months ended September 30, 2018 compared with $2.95 for the same period in 2017, an increase of 15.9%. Annualized returns on average assets, average common equity and average tangible common equity for the nine months ended September 30, 2018 were 1.41%, 8.11% and 16.03%⁽¹⁾, respectively.  Prosperity’s efficiency ratio (excluding credit loss provisions, net gains and losses on the sale of assets and securities and taxes) was 43.88%⁽¹⁾ for the nine months ended September 30, 2018.

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Net interest income before provision for credit losses for the nine months ended September 30, 2018 was $472.345 million compared with $460.813 million for the same period in 2017, an increase of $11.532 million or 2.5%. This change was primarily due to higher loan and investment yields and an increase in loan balances, partially offset by higher rates on interest-bearing liabilities and a decrease in loan discount accretion.

The net interest margin on a tax equivalent basis for the nine months ended September 30, 2018 was 3.20% compared with 3.18% for the same period in 2017.

Noninterest income was $86.933 million for the nine months ended September 30, 2018 compared with $87.413 million for the same period in 2017, a decrease of $480 thousand or 0.5%.

Noninterest expense was $245.416 million for the nine months ended September 30, 2018 compared with $232.013 million for the same period in 2017, an increase of $13.403 million or 5.8%. This increase was primarily due to the 5% salary or pay rate increase for all associates following the enactment of the Tax Cuts and Jobs act.

Balance Sheet Information

At September 30, 2018, Prosperity had $22.613 billion in total assets, an increase of $469.320 million or 2.1%, compared with $22.143 billion at September 30, 2017.

Loans at September 30, 2018 were $10.293 billion, an increase of $381.644 million or 3.9%, compared with $9.911 billion at September 30, 2017. Linked quarter loans increased $146.281 million or 1.4% (5.8% annualized) from $10.147 billion at June 30, 2018.

Deposits at September 30, 2018 were $16.734 billion, a decrease of $173.712 million or 1.0%, compared with $16.907 billion at September 30, 2017. Linked quarter deposits decreased $244.840 million or 1.4% from $16.979 billion at June 30, 2018. This change was primarily due to public funds seasonality.

Asset Quality

Nonperforming assets totaled $16.777 million or 0.08% of quarterly average interest-earning assets at September 30, 2018, compared with $45.823 million or 0.24% of quarterly average interest-earning assets at September 30, 2017, and $31.585 million or 0.16% of quarterly average interest-earning assets at June 30, 2018.

The allowance for credit losses was $85.996 million or 0.84% of total loans at September 30, 2018, $86.812 million or 0.88% of total loans at September 30, 2017 and $84.964 million or 0.84% of total loans at June 30, 2018.  Excluding loans acquired that are accounted for under FASB Accounting Standards Codification (“ASC”) Topics 310-20 and 310-30, the allowance for credit losses was 0.88%⁽¹⁾ of remaining loans as of September 30, 2018, compared with 0.95%⁽¹⁾ at September 30, 2017 and 0.89%⁽¹⁾ at June 30, 2018.

The provision for credit losses was $2.350 million for the three months ended September 30, 2018 compared with $6.900 million for the three months ended September 30, 2017 and $4.000 million for the three months ended June 30, 2018. The provision for credit losses was $15.350 million for the nine months ended September 30, 2018 compared with $12.325 million for the nine months ended September 30, 2017.

Net charge-offs were $1.318 million for the three months ended September 30, 2018 compared with $3.871 million for the three months ended September 30, 2017 and $2.636 million for the three months ended June 30, 2018. Net charge-offs were $13.395 million for the nine months ended September 30, 2018 compared with $10.839 million for the nine months ended September 30, 2017.

Dividend

Prosperity Bancshares, Inc. declared a fourth quarter cash dividend of $0.41 per share to be paid on January 2, 2019 to all shareholders of record as of December 15, 2018, an increase of 13.9% compared with the third quarter 2018 dividend.  

Conference Call

Prosperity’s management team will host a conference call on Wednesday, October 24, 2018 at 11:30 a.m. Eastern Time (10:30 a.m. Central Time) to discuss Prosperity’s third quarter 2018 earnings. Individuals and investment professionals may participate in the call by dialing 877-883-0383. The elite entry number is 6906264.

Alternatively, individuals may listen to the live webcast of the presentation by visiting Prosperity’s website at www.prosperitybankusa.com.  The webcast may be accessed from Prosperity’s home page by selecting “Presentations & Calls” from the drop-down menu on the Investor Relations tab and following the instructions.

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Non-GAAP Financial Measures

Prosperity’s management uses certain non-GAAP financial measures to evaluate its performance. Specifically, Prosperity reviews tangible book value per share, return on average tangible common equity, tangible equity to tangible assets ratio and the efficiency ratio, excluding net gains and losses on the sale of assets and securities.  Further, as a result of acquisitions and the related purchase accounting adjustments, Prosperity uses certain non-GAAP financial measures and ratios that exclude the impact of these items to evaluate its allowance for credit losses to total loans (excluding acquired loans accounted for under ASC Topics 310-20, “Receivables-Nonrefundable Fees and Other Costs” and 310-30, “Receivables-Loans and Debt Securities Acquired with Deteriorated Credit Quality”).  Prosperity believes these non-GAAP financial measures provide information useful to investors in understanding Prosperity’s financial results and that their presentation, together with the accompanying reconciliations, provides a more complete understanding of factors and trends affecting Prosperity’s business and allows investors to view performance in a manner similar to management, the entire financial services sector, bank stock analysts and bank regulators. Further, Prosperity believes that these non-GAAP financial measures provide useful information by excluding certain items that may not be indicative of its core operating earnings and business outlook.  These non-GAAP financial measures should not be considered a substitute for, nor of greater importance than, GAAP basis financial measures and results; Prosperity strongly encourages investors to review its consolidated financial statements in their entirety and not to rely on any single financial measure. Because non-GAAP financial measures are not standardized, it may not be possible to compare these financial measures with other companies’ non-GAAP financial measures having the same or similar names. Please refer to the “Notes to Selected Financial Data” at the end of this Earnings Release for a reconciliation of these non-GAAP financial measures to the nearest respective GAAP financial measures.

Prosperity Bancshares, Inc. ®

As of September 30, 2018, Prosperity Bancshares, Inc. ^® is a $22.613 billion Houston, Texas based regional financial holding company, formed in 1983. Operating under a community banking philosophy and seeking to develop broad customer relationships based on service and convenience, Prosperity offers a variety of traditional loan and deposit products to its customers, which consist primarily of small and medium sized businesses and consumers. In addition to established banking products, Prosperity offers a complete line of services including: Internet Banking services at www.prosperitybankusa.com, Retail Brokerage Services, Credit Cards, Debit Cards, 24 hour voice response banking, Trust and Wealth Management, Mortgage Services, Cash Management and Mobile Banking.

As of September 30, 2018, Prosperity operated 242 full-service banking locations: 65 in the Houston area, including The Woodlands; 29 in the South Texas area including Corpus Christi and Victoria; 33 in the Dallas/Fort Worth area; 22 in the East Texas area; 29 in the Central Texas area including Austin and San Antonio; 34 in the West Texas area including Lubbock, Midland-Odessa and Abilene; 16 in the Bryan/College Station area; 6 in the Central Oklahoma area; and 8 in the Tulsa, Oklahoma area.

“Safe Harbor” Statement under the Private Securities Litigation Reform Act of 1995: This release contains, and the remarks by Prosperity’s management on the conference call may contain, forward-looking statements within the meaning of the securities laws. Forward-looking statements include all statements other than statements of historical fact, including forecasts or trends, and are based on current expectations, assumptions, estimates and projections about Prosperity Bancshares and its subsidiaries.  These forward-looking statements are not guarantees of future performance and are subject to risks and uncertainties, many of which are outside of Prosperity’s control, which may cause actual results to differ materially from those expressed or implied by the forward-looking statements.  These risks and uncertainties include but are not limited to whether Prosperity can: successfully identify acquisition targets and integrate the businesses of acquired companies and banks; continue to sustain its current internal growth rate or total growth rate; provide products and services that appeal to its customers; continue to have access to debt and equity capital markets; and achieve its sales objectives.  Other risks include, but are not limited to: the possibility that credit quality could deteriorate; actions of competitors; changes in laws and regulations (including changes in governmental interpretations of regulations and changes in accounting standards); a deterioration or downgrade in the credit quality and credit agency ratings of the securities in Prosperity’s securities portfolio; customer and consumer demand, including customer and consumer response to marketing; effectiveness of spending, investments or programs; fluctuations in the cost and availability of supply chain resources; economic conditions, including currency rate, interest rate and commodity price fluctuations; and weather.  These and various other factors are discussed in Prosperity Bancshares’ Annual Report on Form 10-K for the year ended December 31, 2017 and other reports and statements Prosperity Bancshares has filed with the SEC. Copies of the SEC filings for Prosperity Bancshares may be downloaded from the Internet at no charge from http://www.prosperitybankusa.com.

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Prosperity Bancshares, Inc.^®

Financial Highlights (Unaudited)

(In thousands)

(A) Includes $586, $436, $57, ($143) and $1,635 in unrealized gains (losses) on available for sale securities for the quarterly periods ended September 30, 2018, June 30, 2018, March 31, 2018, December 31, 2017 and September 30, 2017, respectively.

(B) Includes $463, $345, $45, ($113) and $1,063 in after-tax unrealized gains (losses) on available for sale securities for the quarterly periods ended September 30, 2018, June 30, 2018, March 31, 2018, December 31, 2017 and September 30, 2017, respectively.

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Prosperity Bancshares, Inc.^®

Financial Highlights (Unaudited)

(In thousands)

(C) Interest income on securities was reduced by net premium amortization of $8,073, $7,753, $8,450, $9,521 and $10,115 for the three-month periods ended September 30, 2018, June 30, 2018, March 31, 2018, December 31, 2017 and September 30, 2017, respectively, and $24,276 and $29,401 for the nine-month periods ended September 30, 2018 and September 30, 2017, respectively.

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Prosperity Bancshares, Inc. ^®

Financial Highlights (Unaudited)

(Dollars and share amounts in thousands, except per share data and market prices)

(D) Includes purchase accounting adjustments for the periods presented as follows:

(E) Using effective tax rate of 20.5%, 20.4%, 19.3%, 34.3% and 32.5% for the three-month periods ended September 30, 2018, June 30, 2018,  March 31, 2018, December 31, 2017 and September 30, 2017, respectively, and 20.1% and 32.5% for the nine-month periods ended September 30, 2018 and September 30, 2017, respectively.

(F) Interim periods annualized.

(G) Refer to the "Notes to Selected Financial Data" at the end of this Earnings Release for a reconciliation of this non-GAAP financial measure to the nearest GAAP financial measure.

(H) Net interest margin for all periods presented is based on average balances on an actual 365 day basis.

(I) Calculated by dividing total noninterest expense, excluding credit loss provisions, by net interest income plus noninterest income, excluding net gains and losses on the sale of assets and securities.  Additionally, taxes are not part of this calculation.

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Prosperity Bancshares, Inc.^®

Financial Highlights (Unaudited)

(Dollars in thousands)