Sec Form 4 Filing - COLLINS GARY S @ OLD SECOND BANCORP INC - 2024-03-20

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person COLLINS GARY S 2. Issuer Name and Ticker or Trading Symbol OLD SECOND BANCORP INC [ OSBC] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) VICE CHAIRMAN (Last) (First) (Middle) 37 S. RIVER ST. 3. Date of Earliest Transaction (MM/DD/YY) 03/20/2024 (Street) AURORA, IL60302 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Restricted Stock Units 03/20/2024 A 16,492 ( 1 ) A $ 0 50,330 ( 2 ) D Old Second Bancorp, Inc. Common Stock 104,152.306 ( 3 ) D Old Second Bancorp, Inc. Common Stock 76,768.085 ( 4 ) I IRA Old Second Bancorp, Inc. Common Stock 5,894 I By 401-K

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other COLLINS GARY S 37 S. RIVER ST. AURORA, IL60302 X VICE CHAIRMAN Signatures /s/ Shirley Cantrell, Attorney-in-Fact 03/21/2024 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Each restricted stock grant unit represents a contingent right to receive one share of common stock. The reporting person was granted 16,492 restricted stock units on the date of the grant, 8,246 of which are time-based restricted stock units that vest on the third anniversary of the grant date, and 8,246 of which are performance-based restricted stock units that may vest and convert to shares within a range from 0% to 175% of the underlying performance-based restricted stock units originally awarded, depending on our compensation committee approved performance metrics. Vested shares, if any, will be delivered to the reporting person in 3 to 5 business days from the date of vesting. ( 2 )This total includes 25,165 shares of time-based restricted stock units and 25,165 shares of performance-based restricted stock units. ( 3 )Included in this total are 11,259 shares in Mr. Collins' name alone and 92.893.306 shares held in Mr, Collins' name with a broker. ( 4 )Included in this total are 41,000 shares in a ROTH IRA and 35,768.085 in a traditional IRA.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

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