X0306 4 2021-08-13 0 0001667161 Randolph Bancorp, Inc. RNDB 0001676052 Olson Richard D. Jr. C/O RANDOLPH BANCORP, INC. 2 BATTERYMARCH PARK, SUITE 301 QUINCY MA 02169 0 1 0 0 SVP/Retail & Marketing Common Stock 2021-08-13 4 A 0 2000 0.00 A 12214 D Common Stock 18748 I By IRA Common Stock 1322 I ESOP Stock Options (right to buy) 11.48 2030-08-12 Common Stock 15000 15000 D Stock Options (right to buy) 14.66 2027-10-11 Common Stock 16252 16252 D Acquisition represents an award of restricted stock for no cash consideration. This award vests in three equal annual installments beginning on August 13, 2022. Includes 4,334 shares of restricted stock which vest in annual installments of 2,167 shares from October 12, 2021, 840 shares of restricted stock which vest in annual installments of 210 shares from August 13, 2022 and 2,000 shares of restricted stock which vest in one-third annual installments 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 October 12, 2018. /s/ Lauren B. Messmore 2021-08-13