X0306 4 2022-04-01 0 0001667161 Randolph Bancorp, Inc. RNDB 0001429021 Parent William M C/O RANDOLPH BANCORP, INC. 2 BATTERYMARCH PARK, SUITE 301 QUINCY MA 02169 1 1 0 0 President and CEO Common Stock 2022-04-01 4 F 0 847 26.44 D 23188 D Common Stock 30964 I By IRA Common Stock 146 I ESOP Stock Option (Right to Buy) 11.48 2030-08-12 Common Stock 65000 65000 D Stock Option (Right to Buy) 8.78 2030-03-31 Common Stock 29412 29412 D Represents restricted shares withheld to satisfy the reporting person's tax withholding obligation upon vesting. The deemed disposition of the withheld restricted shares is exempt pursuant to Rule 16b-3(e). Includes 6,000 shares of restricted stock which vest in annual installments of 2,000 shares from April 1, 2023, 10,000 shares of restricted stock which vest in annual installments of 2,500 shares from August 13, 2022 and 1,875 shares of restricted stock which vest in annual installments of 625 shares from August 13, 2022. Updated to reflect the most recent year's allocation of shares. The options vest in five equal annual installments beginning on August 13, 2021. The options vest in five equal annual installments beginning on April 1, 2021. /s/ William M. Parent 2022-04-05