Exhibit 99.1

Mid Penn Bancorp, Inc.

2407 Park Drive

Harrisburg, PA 17110

1-866-642-7736

October 22, 2025 – Harrisburg, PA – Mid Penn Bancorp, Inc. (NASDAQ: MPB) ("Mid Penn"), the parent company of Mid Penn Bank (the "Bank") and MPB Financial Services, LLC, today reported net income available to common shareholders ("earnings") for the quarter ended September 30, 2025, of $18.3 million, or $0.80 per basic and $0.79 per diluted common share, compared to net income of $4.8 million, or $0.22 per basic and diluted common share, for the second quarter of 2025, and exceeded the consensus analyst estimate of $0.71 per diluted common share for the third quarter of 2025.

Key Highlights of the Third Quarter of 2025:

•Net income available to common shareholders increased 48.7% to $18.3 million, or $0.80 per basic and $0.79 per diluted common share, for the third quarter of 2025, compared to net income of $12.3 million, or $0.74 per basic and diluted common share, for the third quarter of 2024. The increase in net income per diluted share was partially offset by the higher number of shares outstanding in 2025, which contributed to the lower year-over-year EPS growth rate. Net income for the nine months ended September 30, 2025 increased 1.6% to $36.8 million, or $1.73 per basic and $1.70 per diluted common share, compared to $36.2 million for the nine months ended September 30, 2024, or $2.18 per basic and diluted common share.

•Net interest margin increased to 3.60% for the quarter ended September 30, 2025, compared to 3.44% for the second quarter of 2025, and 3.13% for the third quarter of 2024. This represents a 16 and 47 basis point ("bp") increase compared to the second quarter of 2025 and third quarter of 2024, respectively. That expansion was accomplished by continued improvement in deposit cost of funds and loan yields over the last nine and twelve months.

•Loan balances declined by $11.8 million, or 1.0% (annualized), during the third quarter of 2025. Total loans increased $378.1 million, or 8.5%, to $4.8 billion at September 30, 2025, compared to $4.4 billion at December 31, 2024. Excluding the William Penn acquisition loans of $431.4 million, the organic loan portfolio as of September 30, 2025 declined $53.3 million or 1.2% from the year ended December 31, 2024. This decline was primarily due to elevated commercial real estate payoffs that outpaced new originations.

•Deposits decreased $106.9 million, or 7.8% (annualized), during the third quarter of 2025, compared to an increase of $717.5 million, or 60.8% (annualized), during the second quarter of 2025. This decrease was driven by a planned exit of approximately $175 million in brokered certificates of deposit to deploy excess liquidity, lower funding costs, and realize gains of $279 thousand on associated interest rate swaps. Additionally, there was a $20.7 million decrease in noninterest-bearing accounts, offset by an $85.3 million increase in interest-bearing transaction accounts. Total deposits increased $652.8 million or 13.9% to $5.3 billion at September 30, 2025, compared to $4.7 billion at December 31, 2024. Excluding the William Penn acquisition deposits of $619.8 million, organic deposit growth as of September 30, 2025 increased $33.0 million or 2.8%, annualized from the year ended December 31, 2024.

•The core efficiency ratio(1) improved to 58.80% in the third quarter of 2025, compared to 62.56% in the second quarter of 2025, and 64.89% in the third quarter of 2024.

•Book value per common share improved to $34.56 as of September 30, 2025, compared to $33.85 as of June 30, 2025, and $34.48 as of September 30, 2024. Tangible book value per common share (1) was $27.96 as of September 30, 2025, compared to $27.22 and $26.36 as of June 30, 2025 and September 30, 2024, respectively.

•On September 24, 2025, Mid Penn entered into an Agreement and Plan of Merger, by and between Mid Penn and 1st Colonial Bancorp, Inc., in a cash and stock deal valued at nearly $101 million. The deal is expected to close in the first or second quarter of 2026, subject to the satisfaction of customary closing conditions, including regulatory approvals and approval by 1st Colonial shareholders.

•On September 25, 2025, Mid Penn entered into an agreement to acquire Cumberland Advisors. Cumberland Advisors, a registered investment advisory firm, recorded a year-to-date annualized revenue of $9.0 million as of the quarter ended June 30, 2025, and is expected to bring approximately $3.3 billion new assets under management to the combined company. The deal is expected to close in the fourth quarter of 2025, subject to customary closing conditions.

•As a result of the foregoing, the Board of Directors declared a cash dividend of $0.22 per common share, payable November 24, 2025, to shareholders of record as of November 10, 2025.

(1) Non-GAAP financial measure. Refer to the calculation in the section titled “Reconciliation of Non-GAAP Measures (Unaudited)” at the end of this document.

Chair, President and CEO Rory G. Ritrievi provided the following statement:

"We are pleased to announce our third quarter results of operations to our shareholders.

Within a quarter that included the announcement of two planned acquisitions, we delivered solid GAAP earnings of $0.80 (per average outstanding share within the quarter), compared to consensus estimate of $0.71 per share, 3Q24 of $0.74 per share and 2Q25 of $0.22 per share.

Our success was driven by a confluence of factors. Through repricing of existing loans, disciplined pricing on new loans, accretion from acquired loans, and a marginal improvement in deposit cost of funds, our net interest margin expanded by 16 basis points within the quarter and is now up to 3.6%. There is still some progress needed to get back to our pre-inverted yield curve days but we have seen great progress over the last seven quarters.

Asset quality was spectacular within the quarter, continuing a trend that has been occurring for several years now. While net charge offs were less than $100,000 for the quarter, nonperforming assets were down slightly from 2Q25.

Annualized revenues for 3Q25 were $247.2 million, versus annualized revenues for 2Q25 of $217.2 million for an annualized increase of $30 million or 13.8%. Solid revenue expansion.

When excluding M&A costs incurred in 2Q25, noninterest expenses were basically flat between the two linked quarters, as evidenced by a 377 basis point decrease in our core efficiency ratio as it declined from 62.6% in 2Q25 to 58.8% in 3Q25.

Good revenue growth + good NIM expansion + flat operating expenses + solid asset quality = a great quarter of performance for Mid Penn, even while shifting some resources toward the announcement of two meaningful M&A transactions.

With all that in mind, I happily announce, on behalf of the Board of Directors, an increase to our quarterly dividend of 10% going up to $0.22 per common share for the 3rd quarter, payable November 24, 2025, to shareholders of record as of November 10, 2025." For the three months ended September 30, 2025, net interest income was $53.6 million, compared to net interest income of $48.2 million for the three months ended June 30, 2025, and $40.2 million for the three months ended September 30, 2024.

Net Interest Income

The tax-equivalent net interest margin for the three months ended September 30, 2025 was 3.60% compared to 3.44% and 3.13% for the second quarter of 2025 and third quarter of 2024, respectively, representing a 16 bp increase from the second quarter of 2025, and a 47 bp increase compared to the same period in 2024.

The yield on interest-earning assets increased to 5.81% for the quarter ended September 30, 2025, from 5.69% for the three months ended June 30, 2025, and 5.73% for the three months ended September 30, 2024. The increase from the second quarter of 2025 was primarily due to an increase in interest income on loans, and an increase in the average balance of Federal Funds Sold.

For the nine months ended September 30, 2025, net interest income increased 25.1% to $144.3 million compared to net interest income of $115.4 million for the same period of 2024. The increase was primarily driven by a $17.9 million increase in interest income on loans, a $4.7 million increase in Federal Funds Sold, and a $9.7 million decrease in interest expense on short-term borrowings, partially offset by a $6.4 million increase in interest expense on deposits, compared to the same period of 2024.

Average Balances

Average balances for the year ended September 30, 2025 continue to be impacted by the William Penn acquisition given that the acquisition closed on April 30, 2025. Day one increases in loans, total assets, deposits, and total liabilities were $431.4 million, $727.7 million, $619.8 million, and $630.2 million, respectively.

Average loans increased $79.5 million to $4.8 billion for the quarter ended September 30, 2025, compared to $4.7 billion for the quarter ended June 30, 2025, and increased $398.2 million compared to $4.4 billion for the quarter ended September 30, 2024.

Average deposits were $5.5 billion for the third quarter of 2025, reflecting an increase of $308.4 million, or 6.0%, compared to total average deposits of $5.2 billion in the second quarter of 2025, and an increase of $870.5 million, or 18.9%, compared to total average deposits of $4.6 billion for the third quarter of 2024. The average cost of deposits was 2.37% for the third quarter of 2025, representing a 2 bp decrease and a 31 bp decrease from the second quarter of 2025 and the third quarter of 2024, respectively.

Cost of funds decreased to 2.39%, compared to 2.44% for the second quarter of 2025. Despite a higher total interest expense, cost of funds improved during the quarter, primarily due to the growth in average noninterest-bearing and interest-bearing demand deposits.

Asset Quality

The total benefit for credit losses, including benefit for credit losses on off-balance sheet credit exposures, was $434.0 thousand for the three months ended September 30, 2025, a decrease of $2.7 million compared to the provision for credit losses of $2.3 million for the three months ended June 30, 2025, and a $950 thousand decrease compared to the provision for credit losses of $516 thousand for the three months ended September 30, 2024. The decrease in provision was primarily driven by lower loan balances as a result of an increase in observed prepayment speeds. Net charge offs for the three months ended September 30, 2025 were $91 thousand, or less than 0.002% of total average loans.

The provision for credit losses on loans was $2.4 million for the nine months ended September 30, 2025, an increase of $595 thousand compared to the provision for credit losses of $1.8 million for the nine months ended September 30, 2024. This increase for the nine months ended September 30, 2025 was primarily due to a $2.3 million reserve on non-PCD loans acquired through the William Penn acquisition, partially offset by lower loan balances as a result of an increase in observed prepayment speeds. The benefit for credit losses on off-balance sheet credit exposures was $247 thousand and $243 thousand for the three and nine months ended September 30, 2025, respectively.

Allowance for credit losses - loans was 0.77%, 0.78%, and 0.80% of loans, net of unearned income at September 30, 2025, June 30, 2025, and September 30, 2024, respectively.

Total nonperforming assets were $27.3 million at September 30, 2025, compared to nonperforming assets of $28.0 million and $17.7 million at June 30, 2025 and September 30, 2024, respectively. The decrease during the third quarter of 2025 primarily related to a decrease in commercial real estate non-accrual loans. Delinquency, measured as loans past due 30 days or more, as a percentage of total loans was 0.68% at September 30, 2025, compared to 0.58% and 0.61% as of June 30, 2025 and September 30, 2024, respectively.

Capital

Shareholders’ equity increased $141.3 million, or 21.6%, from $655.0 million as of December 31, 2024, to $796.3 million as of September 30, 2025. Retained earnings increased $13.7 million, or 7.2%, from $191.6 million as of June 30, 2025 to $205.3 million as of September 30, 2025. Regulatory capital ratios for both Mid Penn and the Bank indicate regulatory capital levels in excess of both the regulatory minimums and the levels necessary for the Bank to be considered "well capitalized" at September 30, 2025. Additionally, Mid Penn declared $4.6 million in dividends during the third quarter of 2025.

On April 23, 2025, Mid Penn’s Board of Directors reauthorized its treasury stock repurchase program ("the Program") effective through April 30, 2026. The Program authorizes the repurchase of up to $15.0 million of Mid Penn’s outstanding common stock. During the nine months ended September 30, 2025, Mid Penn repurchased 70,669 shares of common stock at an average price of $28.45. As of September 30, 2025, Mid Penn repurchased a total of 511,391 shares of common stock at an average price of $23.57 per share under the Program. The Program had approximately $2.9 million remaining available for repurchase as of September 30, 2025.

Noninterest Income

For the three months ended September 30, 2025, noninterest income totaled $8.2 million, an increase of $2.0 million, or 33.2%, compared to noninterest income of $6.1 million for the second quarter of 2025. The increase is primarily due to a $337 thousand increase in mortgage banking, a $114 thousand increase in earnings from the cash surrender value of life insurance, and a $1.6 million increase in other noninterest income, driven by $534 thousand in recoveries on loans previously acquired in business combinations. These recoveries are recognized in noninterest income rather than a reduction to the allowance for credit losses, consistent with purchase accounting treatment, as expected credit losses on acquired loans were reflected in fair value adjustments at the acquisition date. This increase also includes $420 thousand gain on the closing of an investment of a reinsurance entity acquired from another institution, and $279 thousand in swap cancellation gains tied to eliminated brokered deposits.

For the nine months ended September 30, 2025, noninterest income totaled $19.6 million, an increase of $3.2 million, or 19.7%, compared to noninterest income of $16.3 million for the nine months ended September 30, 2024. The increase in noninterest income is primarily driven by a $509 thousand increase in earnings from the cash surrender value of life insurance, a $460 thousand increase in mortgage banking, a $421 thousand increase in fiduciary and wealth management, and a $1.7 million increase in other noninterest income, driven by $534 thousand in recoveries on loans previously acquired in business combinations. These recoveries are recognized in noninterest income rather than a reduction to the allowance for credit losses, consistent with purchase accounting treatment, as expected credit losses on acquired loans were reflected in fair value adjustments at the acquisition date. This increase also includes a $420 thousand gain on the closing of an investment of a reinsurance entity acquired from another institution, and $279 thousand in swap cancellation gains tied to eliminated brokered deposits.

Noninterest Expense

For the three months ended September 30, 2025, noninterest expense totaled $38.0 million, a decrease of $9.8 million, or 20.54%, compared to noninterest expense of $47.8 million in the second quarter of 2025.

Merger and acquisition expenses decreased $10.8 million, primarily reflecting the absence of $11.2 million of merger related expenses related to the William Penn acquisition and $164 thousand related to the Charis Insurance Group acquisition, both of which closed in the second quarter of 2025.

For the nine months ended September 30, 2025, noninterest expense totaled $116.4 million, an increase of $29.7 million, or 34.3%, compared to noninterest expense of $86.7 million for the nine months ended September 30, 2024.

Merger and acquisition expenses increased $11.4 million for the nine months ended September 30, 2025, which includes $11.2 million of merger related expenses related to the William Penn acquisition and $164 thousand related to the Charis Insurance Group acquisition.

Salaries and benefits increased $10.9 million for the nine months ended September 30, 2025, compared to the same period in 2024, The increase is attributable to (i) equity-based compensation expense for stock options and restricted stock awards totaling $2.8 million that were recognized in the nine months ended September 30, 2025; (ii) the retail staff additions at the twelve retail locations added through the William Penn acquisition; and (iii) the retention of various William Penn team members through the completion of systems integration, which occurred on June 20, 2025.

Software licensing and utilization costs increased $2.5 million for the nine months ended September 30, 2025, compared to the same period in 2024. The increase reflects additional costs to (i) license the additional William Penn branches; and (ii) upgrades to internal systems, including network storage, cybersecurity, and data security enhancements in response to the Bank's larger size and increased IT complexity.

Occupancy expenses increased $1.6 million for the nine months ended September 30, 2025, compared to the same period in 2024. The increase was driven by the facility operating costs of the additional retail locations added through the William Penn acquisition.

The core efficiency ratio(1) was 58.8% in the third quarter of 2025, compared to 62.6% in the second quarter of 2025 and 64.9% in the third quarter of 2024. The improvement in the core efficiency ratio during the third quarter of 2025 compared to the second quarter of 2025 was the result of higher net interest income, higher noninterest income and lower noninterest expense. Mid Penn continues to evaluate levels of noninterest expense for opportunities to reduce operating costs throughout the organization.

(1)Non-GAAP financial measure. Refer to the calculation in the section titled “Reconciliation of Non-GAAP Measures (Unaudited)” at the end of this document. Non-GAAP financial measure.

Subsequent Events

Management considers subsequent events occurring after the balance sheet date for matters which may require adjustment to, or disclosure in, the consolidated financial statements. The review period for subsequent events extends up to and including the filing date of a public company’s consolidated financial statements when filed with the Securities and Exchange Commission ("SEC"). Accordingly, the financial information in this announcement is subject to change. The statements are valid only as of the date hereof and Mid Penn disclaims any obligation to update this information.

This press release, and oral statements made regarding the subjects of this release, contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Such statements are not historical facts and include expressions about management's confidence and strategies and management's current views and expectations about new and existing programs and products, relationships, opportunities, technology, and market conditions. These statements may be identified by such forward-looking terminology as "continues," "expect," "look," "believe," "anticipate," "may," "will," "should," "projects," "strategy" or similar statements. Actual results may differ materially from such forward-looking statements, and no reliance should be placed on any forward-looking statement. Factors that may cause results to differ materially from such forward-looking statements include, but are not limited to, changes in interest rates, spreads on earning assets and interest-bearing liabilities, and interest rate sensitivity; prepayment speeds, loan originations, credit losses and market values on loans, collateral securing loans, and other assets; sources of liquidity; common shares outstanding; common stock price volatility; fair value of and number of stock-based compensation awards to be issued in future periods; the impact of changes in market values on securities held in Mid Penn’s portfolio; legislation affecting the financial services industry as a whole, and Mid Penn and Mid Penn Bank individually or collectively, including tax legislation; results of the regulatory examination and supervision process and oversight, including changes in monetary policy and capital requirements; changes in accounting policies or procedures as may be required by the Financial Accounting Standards Board or regulatory agencies; increasing price and product/service competition by competitors, including new entrants; rapid technological developments and changes; the ability to continue to introduce competitive new products and services on a timely, cost-effective basis; the mix of products/services; containing costs and expenses; governmental and public policy changes; protection and validity of intellectual property rights; reliance on large customers; technological, implementation and cost/financial risks in large, multi-year contracts; the outcome of future litigation and governmental proceedings, including tax-related examinations and other matters; continued availability of financing; the availability of financial resources in the amounts, at the times and on the terms required to support Mid Penn and Mid Penn Bank’s future businesses; material differences in the actual financial results of merger, acquisition and investment activities compared with Mid Penn’s initial expectations, including the full realization of anticipated cost savings and revenue enhancements; the occurrence of any event, change or other circumstances that could give rise to the right of one or both of the parties to terminate the respective merger agreement between Mid Penn and 1st Colonial or Cumberland Advisors; the outcome of any legal proceedings that may be instituted against Mid Penn or 1st Colonial; delays in completing the transactions; the failure to obtain necessary regulatory approvals for the 1st Colonial acquisition (and the risk that such approvals may result in the imposition of conditions that could adversely affect the combined company or the expected benefits of the transaction); the failure to obtain 1st Colonial shareholder approval or to satisfy any of the other conditions to the 1st Colonial or Cumberland Advisors transaction on a timely basis or at all; the possibility that the anticipated benefits of a transaction are not realized when expected or at all, including as a result of the impact of, or problems arising from, the integration of the two companies or as a result of the strength of the economy and competitive factors in legacy Mid Penn and target markets; diversion of management’s attention from ongoing business operations and opportunities; potential adverse reactions or changes to business or employee relationships, including those resulting from the announcement or completion of the 1st Colonial or Cumberland Advisors transaction; the ability to complete the integration of Mid Penn and its targets successfully; the dilution caused by Mid Penn’s issuance of additional shares of its capital stock in connection with the 1st Colonial or Cumberland Advisors transaction; and other factors that may affect the future results of Mid Penn, 1st Colonial or Cumberland Advisors.

For a more detailed description of these and other factors which would affect our results, please see Mid Penn’s filings with the SEC, including those risk factors identified in the "Risk Factors" section and elsewhere in our Annual Report on Form 10-K for the year ended December 31, 2024 and subsequent filings with the SEC. The statements in this press release are made as of the date of this press release, even if subsequently made available by Mid Penn on its website or otherwise. Mid Penn does not undertake, and specifically disclaims any obligation, to publicly release the result of any revisions which may be made to forward-looking statements to reflect events or circumstances after the date of such statements or to reflect the occurrence of unanticipated events, except as required by law.

(1)Non-GAAP financial measure. Refer to the calculation in the section titled “Reconciliation of Non-GAAP Measures (Unaudited)” at the end of this document.

(2)Regulatory capital ratios as of September 30, 2025 are preliminary and prior periods are actual.

(3)Annualized ratio

(4)Includes $2.3 million related to non-PCD loans acquired in the William Penn transaction on April 30, 2025.

(1)Presented on a fully taxable-equivalent basis using a 21% federal tax rate and statutory interest expense disallowance.

(2)Annualized ratios

Explanatory note: This press release contains financial information determined by methods other than in accordance with U.S. Generally Accepted Accounting Principles ("GAAP"). Mid Penn’s management uses these non-GAAP financial measures in their analysis of Mid Penn’s performance. For tangible book value, the most directly comparable financial measure calculated in accordance with GAAP is book value. We believe that this measure is important to many investors in the marketplace who are interested in changes from period to period in book value per common share exclusive of changes in intangible assets. Goodwill and other intangible assets have the effect of increasing total book value while not increasing tangible book value. Income tax effects of non-GAAP adjustments are calculated using the applicable statutory tax rate for the jurisdictions in which the charges (benefits) are incurred, while taking into consideration any valuation allowances or non-deductible portions of the non-GAAP adjustments. Adjusted earnings per common share excludes from income available to common shareholders certain expenses related to significant non-core activities, including merger-related expenses, net of income taxes. For return on average tangible common equity, the most directly comparable financial measure calculated in accordance with GAAP is return on average equity. The core efficiency ratio is often used by management to measure its noninterest expense as a percentage of its revenue. This non-GAAP disclosure has limitations as an analytical tool, should not be viewed as a substitute for financial measures determined in accordance with GAAP, and should not be considered in isolation or as a substitute for analysis of Mid Penn’s results and financial condition as reported under GAAP, nor is it necessarily comparable to non-GAAP performance measures that may be presented by other companies. Management believes that this non-GAAP supplemental information will be helpful in understanding Mid Penn’s ongoing operating results. This supplemental presentation should not be construed as an inference that Mid Penn’s future results will be unaffected by similar adjustments to be determined in accordance with GAAP. The reconciliation of the non-GAAP to comparable GAAP financial measures can be found in the tables below.

(1) These recoveries are recognized in noninterest income rather than a reduction to the allowance for credit losses, consistent with purchase accounting treatment, as expected credit losses on acquired loans were reflected in fair value adjustments at the acquisition date.

(1) Annualized ratio

(1) These recoveries are recognized in noninterest income rather than a reduction to the allowance for credit losses, consistent with purchase accounting treatment, as expected credit losses on acquired loans were reflected in fair value adjustments at the acquisition date.