Exhibit (4)(a)

DEPOSIT AGREEMENT

AMONG

S&T BANCORP, INC.

[              ],

as Depositary

and the Holders from time to time of

the Depository Receipts described herein

Dated as of                      ,             

TABLE OF CONTENTS

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TABLE OF CONTENTS (cont’d)

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DEPOSIT AGREEMENT

DEPOSIT AGREEMENT, dated as of                      ,              among S&T BANCORP, INC., a Pennsylvania corporation, [              ], a [              ] corporation, as Depositary, and the holders from time to time of the Receipts described herein.

WITNESSETH

WHEREAS, it is desired to provide, as hereinafter set forth in this Deposit Agreement, for the deposit of shares of Series      [__%] Preferred Stock, no par value per share, of S&T Bancorp, Inc. with the Depositary (as hereinafter defined) for the purposes set forth in this Deposit Agreement and for the issuance hereunder of Receipts (as hereinafter defined) by the Depositary evidencing Depositary Shares in respect of the Stock (as hereinafter defined) so deposited;

NOW, THEREFORE, in consideration of the premises contained herein and such other good and valuable consideration, receipt of which is hereby acknowledged, the parties hereto agree as follows:

ARTICLE I

DEFINITIONS

SECTION 1.1. Definitions.

The following definitions shall for all purposes, unless otherwise indicated, apply to the respective terms used in this Deposit Agreement and the Receipts:

“Certificate of Designation” shall mean the certificate of designation to the Articles of Incorporation, as amended, of the Company filed with the Department of State of the Commonwealth of Pennsylvania establishing the Stock as a series of preferred stock of the Company.

“Company” shall mean S&T Bancorp, Inc., a Pennsylvania corporation, and its successors.

“Deposit Agreement” shall mean this Deposit Agreement, as amended or supplemented from time to time in accordance with the terms hereof.

“Depositary” shall mean [              ], a [              ] corporation, and any successor Depositary hereunder.

“Depositary Shares” shall mean the Depositary Shares, each representing a one-              (1/__th) interest in a share of Stock and which shall be evidenced by Receipts.

“Depositary’s Agent” shall mean an agent appointed by the Depositary pursuant to Section 7.5.

“Depositary’s Office” shall mean the principal office of the Depositary at which at any particular time its depositary business shall be administered.

“Receipt” shall mean one of the depositary receipts, whether in definitive or temporary form, issued hereunder by the Depositary, each representing any number of whole Depositary Shares. [If Receipts are to be issued in Book-Entry Form: If the context so requires, the term “Receipt” shall be deemed to include the DTC Receipt (as defined in Section 2.1 hereof).] “record holder” with respect to a Receipt shall mean the individual, entity or person in whose name a Receipt is registered on the books of the Depositary or any register of any Registrar maintained for such purpose at a given time.

“Registrar” shall mean any bank or trust company which shall be appointed by the Depositary to register ownership and transfers of Receipts as herein provided and which may include the Depositary.

“Securities Act” shall mean the Securities Act of 1933, as amended.

“Stock” shall mean shares of the Company’s Series      [              %] Preferred Stock, no par value per share.

ARTICLE II

FORM OF RECEIPTS; DEPOSIT OF STOCK; EXECUTION AND

DELIVERY, TRANSFER, SURRENDER AND REDEMPTION OF RECEIPTS

[Use bracketed portions only if Receipts are to be issued in Book-Entry Form]

Section 2.1. [Book-Entry Form;] Form and Transfer of Receipts .

(a) [[All] [A portion] of the Receipts shall initially be represented by one or more global receipts (collectively, the “DTC Receipt”) deposited with The Depository Trust Company (“DTC”) and registered in the name of [Cede & Co.], a nominee of DTC. The Depositary, or such other entity as is agreed to by DTC, may hold the DTC Receipt as custodian for DTC. So long as the Receipts are eligible for book-entry settlement with DTC, except as provided for in Section 2.9 hereof, no person acquiring Depositary Shares traded on any securities exchange with book-entry settlement through DTC shall receive or be entitled to receive physical delivery of the Receipts evidencing such Depositary Shares. Ownership of beneficial interests in the DTC Receipt shall be shown on, and the transfer of such ownership shall be effected through, records maintained by (i) DTC or its nominee for such DTC Receipt, or (ii) institutions that have accounts with DTC.]

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(b) [If DTC subsequently ceases to make its book-entry settlement system available for the Receipts, the Company may instruct the Depositary regarding making other arrangements for book-entry settlement. In the event that the Receipts are not eligible for, or it is no longer necessary to have the Receipts available in, book-entry form, the Depositary shall provide written instructions to DTC to deliver to the Depositary for cancellation the DTC Receipt, and the Company shall instruct the Depositary to deliver to the beneficial owners of the Depositary Shares previously evidenced by the DTC Receipt definitive receipts in physical form evidencing such Depositary Shares. Such definitive Receipts shall be in the form annexed hereto as Exhibit A with appropriate insertions, modifications and omissions, as hereafter provided.]

(c) The beneficial owners of Depositary Shares shall [, except as stated above with respect to Depositary Shares in book-entry form represented by the DTC Receipt,] be entitled to receive Receipts in physical, certificated form as herein provided.

(d) [The Receipts may be typewritten in the case of the DTC Receipts and otherwise shall, upon notice by the Company to the Depositary, be definitive Receipts.] Definitive Receipts shall be engraved or printed or lithographed on steel-engraved borders and shall be substantially in the form annexed hereto as Exhibit A, with appropriate insertions, modifications and omissions, as hereinafter provided. [If Receipts are to be issued in Book-Entry Form: The DTC Receipt shall bear such legend or legends as may be required by DTC in order for it to accept the Depositary Shares for its book-entry settlement system.] Pending the preparation of definitive Receipts, the Depositary, upon the written order of the Company [If shares of Stock may be deposited by holders thereof: or any holder of Stock, as the case may be,] delivered in compliance with Section 2.2, shall execute and deliver temporary Receipts which shall be printed, lithographed, typewritten, mimeographed or otherwise substantially of the tenor of the definitive Receipts in lieu of which they are issued and with such appropriate insertions, omissions, substitutions and other variations as the persons executing such Receipts may determine, as evidenced by their execution of such Receipts. After the preparation of definitive Receipts, the temporary Receipts shall be exchangeable for definitive Receipts upon surrender of the temporary Receipts at the Depositary’s Office, without charge to the holder. Upon surrender for cancellation of any one or more temporary Receipts, the Depositary shall execute and deliver in exchange therefor definitive Receipts representing the same number of Depositary Shares as represented by the surrendered temporary Receipt or Receipts registered in the name (and only the name) of the holder of the temporary Receipt. Such exchange shall be made at the Company’s expense and without any charge therefor to the holder. Until so exchanged, the temporary Receipts shall in all respects be entitled to the same benefits under this Deposit Agreement and with respect to the Stock, as definitive Receipts.

(e) Receipts shall be executed by the Depositary by the manual signature of a duly authorized officer of the Depositary; provided, that such signature may be a facsimile if a Registrar for the Receipts (other than the Depositary) shall have been appointed and such Receipts are countersigned by manual signature of a duly authorized officer of the Registrar. No Receipt shall be entitled to any benefits under this Deposit Agreement or be valid or obligatory for any purpose unless it shall have been executed manually by a duly

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authorized officer of the Depositary or, if a Registrar for the Receipts (other than the Depositary) shall have been appointed, by facsimile signature of a duly authorized officer of the Depositary and countersigned manually by a duly authorized officer of such Registrar. The Depositary shall record on its books each Receipt so signed and delivered as hereinafter provided. Receipts bearing the manual or facsimile signatures of individuals who were at any time proper officers of the Depositary or the Registrar, as the case may be, shall constitute adequate signatures hereunder, notwithstanding that such individuals or any of them have ceased to hold such offices prior to the delivery of such Receipts or did not hold such offices on the date of delivery of such Receipts.

Receipts shall be in denominations of any number of whole Depositary Shares.

(f) Receipts may be endorsed with or have incorporated in the text thereof such legends or recitals or changes not inconsistent with the provisions of this Deposit Agreement as may be required by the Depositary and approved by the Company or required to comply with any applicable law or regulation or with the rules and regulations of any securities exchange upon which the Stock, the Depositary Shares or the Receipts may be listed or to conform with any usage with respect thereto, or to indicate any special limitations or restrictions to which any particular Receipts are subject.

(g) [Subject to any limitations set forth in a Receipt or in this Deposit Agreement,] Title to Depositary Shares evidenced by a Receipt