Exhibit 99.1

FOR IMMEDIATE RELEASE

PROSPERITY BANCSHARES, INC.^®

REPORTS FOURTH QUARTER

2018 EARNINGS

HOUSTON, January 30, 2019. Prosperity Bancshares, Inc.^® (NYSE: PB), the parent company of Prosperity Bank^® (collectively, “Prosperity”), reported net income for the quarter ended December 31, 2018 of $83.331 million, an increase of $16.193 million or 24.1% compared with $67.138 million for the same period in 2017. Net income per diluted common share increased 22.7% to $1.19 compared with $0.97 for the same period in 2017. Additionally, loans increased 3.5% during 2018 and nonperforming assets remain low at 0.10% of fourth quarter average interest-earning assets.

“We are extremely proud that Prosperity Bank has once again been ranked in the Top 10 of Forbes Best Banks in America for 2019, making Prosperity the only bank in the country to have been ranked in the Top 10 every year from 2014 to 2019,” said David Zalman, Prosperity’s Chairman and Chief Executive Officer.

“Prosperity’s earnings per share increased 22.7% in the fourth quarter 2018 compared to the fourth quarter of 2017.  For 2018, loans increased $349.5 million, or 3.5%, and average noninterest bearing deposits increased $303.5 million, or 5.7%.  Further, our asset quality remains one of the best in the industry, with non-performing loans at 0.10% of fourth quarter 2018 average interest earning assets,” continued Zalman.

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“Texas and Oklahoma continue to experience employment and population growth, with many companies moving to these states because of favorable tax environments and business friendly political climates. We look forward to the opportunities ahead in 2019. We will continue our focus on organic growth and serving our customers and communities, while also pursuing strategic acquisition opportunities,” concluded Zalman.

Results of Operations for the Three Months Ended December 31, 2018

Net income was $83.331 million⁽²⁾ for the three months ended December 31, 2018 compared with $67.138 million⁽³⁾ for the same period in 2017, an increase of $16.193 million or 24.1%. Net income per diluted common share was $1.19 for the three months ended December 31, 2018 compared with $0.97 for the same period in 2017, an increase of 22.7%. Annualized returns on average assets, average common equity and average tangible common equity for the three months ended December 31, 2018 were 1.47%, 8.25% and 15.84%⁽¹⁾, respectively.  Prosperity’s efficiency ratio (excluding credit loss provisions, net gains and losses on the sale of assets and taxes) was 43.20%⁽¹⁾ for the three months ended December 31, 2018.

Net interest income before provision for credit losses for the three months ended December 31, 2018 was $157.248 million compared with $156.050 million for the same period in 2017, an increase of $1.198 million or 0.8%. Net interest income was impacted by a decrease in loan discount accretion of $1.893 million. Linked quarter net interest income before provision for credit losses decreased $71 thousand to $157.248 million compared with $157.319 million for the three months ended September 30, 2018.

The net interest margin on a tax equivalent basis was 3.15% for the three months ended December 31, 2018 compared with 3.20% for the same period in 2017 and 3.15% for the three months ended September 30, 2018. The change compared with the fourth quarter 2017 was primarily due to higher rates on interest-bearing liabilities and a decrease in loan discount accretion, partially offset by higher yields on interest-earning assets.

Noninterest income was $29.079 million for the three months ended December 31, 2018 compared with $29.220 million for the same period in 2017, a decrease of $141 thousand or 0.5%. On a linked quarter basis, noninterest income decreased $1.545 million or 5.0% to $29.079 million compared with $30.624 million for the three months ended September 30, 2018. This decrease was primarily due to the net loss on sale of assets and a decrease in other noninterest income.

Noninterest expense was $80.804 million for the three months ended December 31, 2018 compared with $81.088 million for the same period in 2017, a decrease of $284 thousand or 0.4%. On a linked quarter basis, noninterest expense decreased $956 thousand or 1.2% to $80.804 million compared with $81.760 million for the three months ended September 30, 2018. This change was primarily due to a decrease in regulatory assessments and FDIC insurance resulting from the elimination of the FDIC temporary surcharge imposed on large banks by the Dodd-Frank Act.

Results of Operations for the Year Ended December 31, 2018

Net income was $321.812 million⁽⁴⁾ for the year ended December 31, 2018 compared with $272.165 million⁽⁵⁾ for the same period in 2017, an increase of $49.647 million or 18.2%.  Net income per diluted common share was $4.61 for the year ended December 31, 2018 compared with $3.92 for the same period in 2017, an increase of 17.6%. Annualized returns on average assets, average common equity and average tangible common equity for the year ended December 31, 2018 were 1.42%, 8.15% and 16.00%⁽¹⁾, respectively.  Prosperity’s efficiency ratio (excluding credit loss provisions, net gains and losses on the sale of assets and securities and taxes) was 43.71%⁽¹⁾ for the year ended December 31, 2018.

Net interest income before provision for credit losses for the year ended December 31, 2018 was $629.593 million compared with $616.863 million for the same period in 2017, an increase of $12.730 million or 2.1%. Net interest income was impacted by a decrease in loan discount accretion of $7.997 million.

The net interest margin on a tax equivalent basis for the year ended December 31, 2018 was 3.18% compared with 3.19% for the same period in 2017.

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Noninterest income was $116.012 million for the year ended December 31, 2018 compared with $116.633 million for the same period in 2017, a decrease of $621 thousand or 0.5%. This decrease was primarily due to the gain on sale of securities during 2017, partially offset by a lower net loss on sale of assets during 2018.

Noninterest expense was $326.220 million for the year ended December 31, 2018 compared with $313.101 million for the same period in 2017, an increase of $13.119 million or 4.2%. This increase was primarily due to higher salaries and benefits.

Balance Sheet Information

At December 31, 2018, Prosperity had $22.693 billion in total assets, an increase of $106.110 million or 0.5%, compared with $22.587 billion at December 31, 2017.

Loans at December 31, 2018 were $10.370 billion, an increase of $349.540 million or 3.5%, compared with $10.021 billion at December 31, 2017. Linked quarter loans increased $77.467 million or 0.8% (3.0% annualized) from $10.293 billion at September 30, 2018.

Deposits at December 31, 2018 were $17.257 billion, a decrease of $564.902 million or 3.2%, compared with $17.821 billion at December 31, 2017. This was primarily due to lower municipal deposits compared with the prior year. Linked quarter deposits increased $522.794 million or 3.1% from $16.734 billion at September 30, 2018. This change was primarily due to seasonality.

Asset Quality

Nonperforming assets totaled $18.956 million or 0.10% of quarterly average interest-earning assets at December 31, 2018, compared with $37.455 million or 0.19% of quarterly average interest-earning assets at December 31, 2017, and $16.777 million or 0.08% of quarterly average interest-earning assets at September 30, 2018.

The allowance for credit losses was $86.440 million or 0.83% of total loans at December 31, 2018, $84.041 million or 0.84% of total loans at December 31, 2017 and $85.996 million or 0.84% of total loans at September 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 December 31, 2018, compared with 0.91%⁽¹⁾ at December 31, 2017 and 0.88%⁽¹⁾ at September 30, 2018.

The provision for credit losses was $1.000 million for the three months ended December 31, 2018 compared with $2.000 million for the three months ended December 31, 2017 and $2.350 million for the three months ended September 30, 2018. The provision for credit losses was $16.350 million for the year ended December 31, 2018 compared with $14.325 million for the year ended December 31, 2017.

Net charge-offs were $556 thousand for the three months ended December 31, 2018 compared with $4.771 million for the three months ended December 31, 2017 and $1.318 million for the three months ended September 30, 2018. Net charge-offs were $13.951 million for the year ended December 31, 2018 compared with $15.610 million for the year ended December 31, 2017.

Dividend

Prosperity Bancshares, Inc. declared a first quarter cash dividend of $0.41 per share to be paid on April 1, 2019 to all shareholders of record as of March 15, 2019.  

Conference Call

Prosperity’s management team will host a conference call on Wednesday, January 30, 2019 at 11:30 a.m. Eastern Time (10:30 a.m. Central Time) to discuss Prosperity’s fourth quarter 2018 earnings. Individuals and investment professionals may participate in the call by dialing 877-883-0383 for domestic participants, or 412-902-6506 for international participants. The elite entry number is 7034870.

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 December 31, 2018, Prosperity Bancshares, Inc. ^® is a $22.693 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 December 31, 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 $392, $586, $436, $57 and ($143) in unrealized gains (losses) on available for sale securities for the quarterly periods ended December 31, 2018, September 30, 2018, June 30, 2018, March 31, 2018 and December 31, 2017, respectively.

(B) Includes $310, $463, $345, $45 and ($113) in after-tax unrealized gains (losses) on available for sale securities for the quarterly periods ended December 31, 2018, September 30, 2018, June 30, 2018, March 31, 2018 and December 31, 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 $7,338, $8,073, $7,753, $8,450 and $9,521 for the three-month periods ended December 31, 2018, September 30, 2018, June 30, 2018, March 31, 2018 and December 31, 2017, respectively, and $31,614 and $38,922 for the years ended December 31, 2018 and December 31, 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 20.3%, 20.5%, 20.4%, 19.3% and 34.3% for the three-month periods ended December 31, 2018, September 30, 2018, June 30, 2018,  March 31, 2018 and December 31, 2017, respectively, and 20.2% and 33.0% for the years ended December 31, 2018 and December 31, 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)