X0306 4 2020-02-21 0 0000357173 OLD SECOND BANCORP INC OSBC 0001184766 COLLINS GARY S 37 S. RIVER ST. AURORA IL 60506 1 1 0 0 Vice Chairman Old Second Bancorp, Inc. Common Stock 2020-02-21 4 D 0 2380 D 98688.306 D Old Second Bancorp, Inc. Common Stock 889 I 401k Plan Old Second Bancorp, Inc. Common Stock 73648.085 I IRA Included in this total are 2,620 shares in Mr. Collins name alone, 28,530 shares of restricted stock units, 25,000 shares of Performance Based restricted stock units and 42,538.306 shares in Mr. Collins name in a broker account. Included in this total are 40,000 shares in a ROTH IRA and 33,648.085 in a traditional IRA. Does not apply. These shares represent vested Restricted Stock Units disposed of to cover a tax liability. /s/ Gary Collins 2020-02-21