X0609 4 2024-04-01 0001403475 Bank of Marin Bancorp BMRC 0001403064 Colombo Russell A false 504 REDWOOD BLVD., SUITE 100 NOVATO CA 94947 true false false false 0 Common Stock 43560 I As Trustee of Colombo Family Trust Common Stock 2551 D Common Stock 13692 I By IRA Stock Options (Right to Buy) 22.94 2024-04-01 4 H 0 8400 0 D 2019-04-01 2024-04-01 Common Stock 8400 0 D Stock Options (Right to Buy) 25.38 2025-03-02 4 H 0 14340 0 D 2018-03-02 2025-03-02 Common Stock 14340 0 D Stock Options (Right to Buy) 24.83 2026-03-01 4 H 0 14820 0 D 2019-03-01 2026-03-01 Common Stock 14820 0 D Stock Options (Right to Buy) 34.80 2027-03-01 Common Stock 10360 10360 D Stock Options (Right to Buy) 33.58 2028-03-01 Common Stock 5420 5420 D Stock Options (Right to Buy) 33.58 2028-03-01 Common Stock 11540 11540 D Stock Options (Right to Buy) 44.45 2029-03-01 Common Stock 10030 10030 D Stock Options (Right to Buy) 40.10 2030-03-02 Common Stock 7430 7430 D Stock Options (Right to Buy) 38.25 2031-03-01 Common Stock 4723 4723 D The stock option was granted on April 1, 2014 and vested in equal annual installments over five years, becoming fully exercisable on April 1, 2019. The option expired unexercised on April 1, 2024. This Form 4 is being filed late due to an administrative oversight. Exercisable 20% per year beginning on first anniversary date of grant. The stock option was granted on March 2, 2015 and vested in equal annual installments over three years, becoming fully exercisable on March 2, 2018. The option expired unexercised on March 2, 2025. This Form 4 is being filed late due to an administrative oversight. Exercisable 33% per year beginning on first anniversary date of grant. The stock option was granted on March 1, 2016 and vested in equal annual installments over three years, becoming fully exercisable on March 1, 2019. The option expired unexercised on March 1, 2026. This Form 4 is being filed late due to an administrative oversight. Exercisable 33% per year beginning on first anniversary date of grant. /s/ Krissy Meyer, Attorney-in-Fact 2026-05-06