Exhibit 99.1

FOR IMMEDIATE RELEASE

PROSPERITY BANCSHARES, INC.^®

REPORTS SECOND QUARTER

2018 EARNINGS

HOUSTON, July 25, 2018. Prosperity Bancshares, Inc.^® (NYSE: PB), the parent company of Prosperity Bank^® (collectively, “Prosperity”), reported net income for the quarter ended June 30, 2018 of $81.597 million, an increase of $13.043 million or 19.0% compared with $68.554 million for the same period in 2017. Net income per diluted common share increased 18.2% to $1.17 compared with $0.99 for the same period in 2017. Additionally, loans increased 5.4% (annualized) during the second quarter of 2018 and nonperforming assets remain low at 0.16% of second quarter average interest-earning assets.

“For the second quarter of 2018, we showed impressive returns on second quarter average tangible common equity of 16.48% annualized and on second quarter average assets of 1.44% annualized,” said David Zalman, Prosperity’s Chairman and Chief Executive Officer.

“The Texas economy continues with vibrant growth helped by the diversity of businesses, no state income tax, a political climate friendly toward business and a strong tailwind from an ever improving energy industry.  In fact, Texas was recently named the Top State for Business in America by CNBC.  The Oklahoma economy is also boosted by its low state income tax, the improving energy industry and a 3.9% unemployment rate for June 2018,” continued Zalman.  

“The Dallas Federal Reserve Bank projects 3.0% job growth for Texas in 2018, or 370,000 new jobs.  Houston is making a comeback with an expected 3.7% job growth in 2018, or 113,000 new jobs. Unemployment rates remain low in Texas and business continues to expand.  The Houston Port Authority reported that they are busier than they have ever been, processing 9,200 trucks in one day, and continue to purchase additional equipment, docks and cranes.  Further, car sales increased approximately 6.0% in Texas and more in Houston,” added Zalman.

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“Overall, we continue to see positive customer sentiment with the reductions in income taxes and in government oversight and regulatory burden.  Business people continue to tell me that for the first time in a number of years, they are able to spend their time growing their businesses,” stated Zalman.

“I would like to thank all of our customers, associates, directors and shareholders for helping make such a successful Bank.  Prosperity Bank was rated by Forbes as one of the Best Banks In America again for 2018, and is the only Texas-based bank in the Top 10.  The Bank has been rated in the Top 10 for five consecutive years and was the highest rated Texas-based bank for the past five years,” concluded Zalman.

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

Net income was $81.597 million⁽²⁾ for the three months ended June 30, 2018 compared with $68.554 million⁽³⁾ for the same period in 2017, an increase of $13.043 million or 19.0%. Net income per diluted common share was $1.17 for the three months ended June 30, 2018 compared with $0.99 for the same period in 2017, an increase of 18.2%. Annualized returns on average assets, average common equity and average tangible common equity for the three months ended June 30, 2018 were 1.44%, 8.33% and 16.48%⁽¹⁾, respectively.  Prosperity’s efficiency ratio (excluding credit loss provisions, net gains and losses on the sale of assets and securities and taxes) was 43.95%⁽¹⁾ for the three months ended June 30, 2018.

Net interest income before provision for credit losses for the three months ended June 30, 2018 was $161.803 million compared with $152.231 million during the same period in 2017, an increase of $9.572 million or 6.3%. This change was primarily due to higher loan and investment yields and an increase in loan balances, partially offset by higher deposit rates. Linked quarter net interest income before provision for credit losses increased $8.580 million or 5.6% to $161.803 million compared with $153.223 million during the three months ended March 31, 2018. This increase was primarily due to higher loan yield and an increase in loan discount accretion, partially offset by higher deposit rates.

The net interest margin on a tax equivalent basis was 3.28% for the three months ended June 30, 2018 compared with 3.14% for the same period in 2017 and 3.16% for the three months ended March 31, 2018. The net interest margin for the three months ended June 30, 2018 was positively impacted by the collection of previously identified troubled assets.

Noninterest income was $28.371 million for the three months ended June 30, 2018 compared with $27.780 million for the same period in 2017, an increase of $591 thousand or 2.1%. On a linked quarter basis, noninterest income increased $433 thousand or 1.5% to $28.371 million compared with $27.938 million  during the three months ended March 31, 2018.

Noninterest expense was $83.602 million for the three months ended June 30, 2018 compared with $76.442 million for the same period in 2017, an increase of $7.160 million or 9.4%. On a linked quarter basis, noninterest expense increased $3.548 million or 4.4% to $83.602 million compared with $80.054 million during the three months ended March 31, 2018. The change during both of these periods was due to an increase in salaries and benefits.  

Results of Operations for the Six Months Ended June 30, 2018

Net income was $155.958 million⁽⁴⁾ for the six months ended June 30, 2018 compared with $137.119 million⁽⁵⁾ for the same period in 2017, an increase of $18.839 million or 13.7%.  Net income per diluted common share was $2.23 for the six months ended June 30, 2018 compared with $1.97 for the same period in 2017, an increase of 13.2%. Annualized returns on average assets, average common equity and average tangible common equity for the six months ended June 30, 2018 were 1.38%, 8.01% and 15.96%⁽¹⁾, respectively.  Prosperity’s efficiency ratio (excluding credit loss provisions, net gains and losses on the sale of assets and securities and taxes) was 44.07%⁽¹⁾ for the six months ended June 30, 2018.

Net interest income before provision for credit losses for the six months ended June 30, 2018 was $315.026 million compared with $304.666 million for the same period in 2017, an increase of $10.360 million or 3.4%. This change was primarily due to higher loan and investment yields and an increase in loan balances, partially offset by higher deposit rates.

The net interest margin on a tax equivalent basis for the six months ended June 30, 2018 was 3.22% compared with 3.17% for the same period in 2017.

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Noninterest income was $56.309 million for the six months ended June 30, 2018 compared with $58.604 million for the same period in 2017, a decrease of $2.295 million or 3.9%. This change was primarily due to the net gain on sale of securities during the six months ended June 30, 2017, partially offset by the net loss on sale of assets during the same period.

Noninterest expense was $163.656 million for the six months ended June 30, 2018 compared with $154.504 million for the same period in 2017, an increase of $9.152 million or 5.9%.  This change was primarily due to an increase in salaries and benefits.

Balance Sheet Information

At June 30, 2018, Prosperity had $22.571 billion in total assets compared with $22.297 billion at June 30, 2017.

Loans at June 30, 2018 were $10.147 billion, an increase of $282.546 million or 2.9%, compared with $9.864 billion at June 30, 2017. Linked quarter loans increased $135.149 million or 1.3% (5.4% annualized) from $10.011 billion at March 31, 2018.

Deposits at June 30, 2018 were $16.979 billion, a decrease of $91.926 million or 0.5%, compared with $17.071 billion at June 30, 2017. Linked quarter deposits decreased $354.275 million or 2.0% from $17.333 billion at March 31, 2018. This change was partially due to seasonality.

Asset Quality

Nonperforming assets totaled $31.585 million or 0.16% of quarterly average interest-earning assets at June 30, 2018, compared with $47.618 million or 0.24% of quarterly average interest-earning assets at June 30, 2017, and $33.217 million or 0.17% of quarterly average interest-earning assets at March 31, 2018.

The allowance for credit losses was $84.964 million or 0.84% of total loans at June 30, 2018, $83.783 million or 0.85% of total loans at June 30, 2017 and $83.600 million or 0.84% of total loans at March 31, 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 0.89%⁽¹⁾ of remaining loans as of June 30, 2018, compared with 0.93%⁽¹⁾ at June 30, 2017 and 0.90%⁽¹⁾ at March 31, 2018.

The provision for credit losses was $4.000 million for the three months ended June 30, 2018 compared with $2.750 million for the three months ended June 30, 2017 and $9.000 million for the three months ended March 31, 2018. The provision for credit losses was $13.000 million for the six months ended June 30, 2018 compared with $5.425 million for the six months ended June 30, 2017.

Net charge-offs were $2.636 million for the three months ended June 30, 2018 compared with $3.062 million for the three months ended June 30, 2017 and $9.441 million for the three months ended March 31, 2018. Net charge-offs for the second quarter of 2018 were primarily comprised of one commercial and industrial loan and one commercial real estate loan. Net charge-offs were $12.077 million for the six months ended June 30, 2018 compared with $6.968 million for the six months ended June 30, 2017.

Dividend

Prosperity Bancshares, Inc. declared a third quarter cash dividend of $0.36 per share to be paid on October 1, 2018 to all shareholders of record as of September 15, 2018.  

Conference Call

Prosperity’s management team will host a conference call on Wednesday, July 25, 2018 at 11:30 a.m. Eastern Time (10:30 a.m. Central Time) to discuss Prosperity’s second quarter 2018 earnings. Individuals and investment professionals may participate in the call by dialing 877-883-0383. The elite entry number is 9749565.

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 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 June 30, 2018, Prosperity Bancshares, Inc. ^® is a $22.571 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 June 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 $436, $57, ($143), $1,635 and $2,871 in unrealized gains (losses) on available for sale securities for the quarterly periods ended June 30, 2018, March 31, 2018, December 31, 2017, September 30, 2017 and June 30, 2017, respectively.

(B) Includes $345, $45, ($113), $1,063 and $1,866 in after-tax unrealized gains (losses) on available for sale securities for the quarterly periods ended June 30, 2018, March 31, 2018, December 31, 2017, September 30, 2017 and June 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 $7,753, $8,450, $9,521, $10,115 and $9,403 for the three-month periods ended June 30, 2018, March 31, 2018, December 31, 2017, September 30, 2017 and June 30, 2017, respectively, and $16,203 and $19,286 for the six-month periods ended June 30, 2018 and June 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 20.4%, 19.3%, 34.3%, 32.5% and 32.0% for the three-month periods ended June 30, 2018,  March 31, 2018, December 31, 2017, September 30, 2017 and June 30, 2017, respectively, and 19.9% and 32.6% for the six-month periods ended June 30, 2018 and June 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)