Investor Presentaiton

| Total Assets and Loans As of March 31, 2021 Total Assets ($M) $2,856 $2,101 $1,950 $4,253 $3.949 2017 2018 2019 2020 2021 Total Loans ($M) 5.25-Year Loans CAGR (through 2021) +20.6% $2,227 $1,560 $1,351 Consumer 1.1% Residential- Fixed Rate 17.4% Construction 4.6% $3,154 $3,180 CRE 39.4% 2017 2018 2019 2020 2021 Loan Portfolio Residential- Adjustable Rate 22.4% Home Equity 3.1% Commercial & Industrial 12.0% $3.2B outstanding as of March 31, 2021 55.1% Commercial 44.9% Consumer 3.74% Q1 2021 average yield excluding fair value accretion CAMBRIDGE BANCORP 2019 and 2020 include acquired balances from Optima Bank & Trust Company, and Wellesley Bancorp, Inc., respectively. 11

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