Item 8.01 Other Events


On June 28, 2021, American River Bankshares, a California corporation (the
"Company" or "AMRB") filed with the Securities and Exchange Commission ("SEC") a
definitive proxy statement (the "Definitive Proxy Statement"), with respect to
the special meeting of shareholders of the Company to be held on July 28, 2021
in connection with the Company's proposed merger (the "Merger") with Bank of
Marin Bancorp, a California corporation ("Marin Bancorp" or "BMRC"), upon the
terms and subject to the conditions set forth in the Agreement to Merge and Plan
of Reorganization, dated April 16, 2021, by and between the Company and Marin
Bancorp.



Important information concerning the special meeting and the proposed Merger is
set forth in the Definitive Proxy Statement. The Definitive Proxy Statement is
amended and supplemented by, and should be read as part of, and in conjunction
with, the information set forth in this Current Report on Form 8-K.  Nothing in
this Current Report on Form 8-K shall be deemed an admission of the legal
necessity or materiality under applicable laws of the disclosures set forth
herein.



1.      The disclosure under the heading "Joint Proposal 1 - The Merger -
Opinion of AMRB's Financial Advisor- Comparable Company Analyses" is hereby
amended by deleting the table of company names in the middle of page 51 (the
AMRB Peer Group) of the joint proxy statement/prospectus and replacing it with
the following:



Financials as of December 31, 2020                                             Market Data (as of 04/15/2021)           LTM Profitability         Balance Sheet Ratios
                                                                                      Price /
                                                                                    Tang.                   1 Yr
                                                                       Total   Mkt   Book    LTM   Div.    Price      Eff.                        

TCE/ Loan/ NPAs/


Assets   Cap  Value    EPS  Yield        ?     Ratio   NIM  ROAA  ROAE     

   TA   Dpts    Assets
Company Name                            City, St           Ticker       ($M)  ($M)    (%)    (x)    (%)      (%)       (%)   (%)   (%)   (%)        (%)    (%)       (%)

Publicly-Traded California Banks with Total Assets $0.60 to $1.25 Billion



Suncrest Bank                           Visalia, CA        SBKK        1,246   155    122   12.0    0.0     61.4        50  3.69  1.10   8.2       10.6     79      0.33
Valley Republic Bancorp                 Bakersfield, CA    VLLX        1,236   130    136    9.3    0.0     87.5        48  3.13  1.12  14.5        7.7     78      0.35
Plumas Bancorp                          Reno, NV           PLBC        1,112   148    149   10.3    2.0     68.0        50  4.02  1.43  15.5        9.0     73      0.35
United Security Bancshares              Fresno, CA         UBFO        1,093   133    118   14.8    5.6     29.4        58  3.39  0.86   7.5       10.4     69      1.56
Community West Bancshares               Goleta, CA         CWBC         

975   110    125   13.4    1.9    117.6        68  3.89  0.85   9.7        9.0    112      0.76
American Riviera Bank                   Santa Barbara, CA  ARBV          972    94    121   13.0    0.0     56.2        65  3.97  0.86   9.2        8.2     83      0.35
Communities First Financial Corporation Fresno, CA         CFST          871   127    181   10.9    0.0     99.8        45  3.92  1.60  19.3        7.9     85      0.24
Summit State Bank                       Santa Rosa, CA     SSBI          866    99    142    9.4    2.9    112.5        52  3.91  1.33  14.7        8.1    104      0.28
1st Capital Bancorp                     Salinas, CA        FISB          833    75    101   16.7    0.0     37.9        68  3.62  0.63   6.3        8.9     81      0.15
US Metro Bank1                          Garden Grove, CA   USMT          767    53     88   12.0    0.0     32.7        56  3.32  0.81   7.6       11.4     89      0.25
Bank of San Francisco                   San Francisco, CA  BSFO          674    51    113   10.9    0.0     21.8        51  3.42  0.85  10.8        6.8    102      0.33
Bay Community Bancorp                   Oakland, CA        CBOB.A        634    61    100   12.7    0.0     43.1        59  3.65  0.84   8.3        7.6     92      0.04
Pinnacle Bank                           Gilroy, CA         PBNK         

618 68 115 17.5 0.0 59.4 67 3.84 0.71 7.1 9.4 88 0.01 Pacific Enterprise Bancorp

Irvine, CA         PEBN          

604 58 103 18.9 0.0 50.0 73 4.10 0.51 5.2 9.4 118 0.00

1) US Metro Bank financial data shown bank-level

Note: Institutions are not pro forma for pending / recently completed M&A and / or capital raises that occurred after period end; Excludes merger targets

Source: S&P Global Market Intelligence









2.      The disclosure under the heading "Joint Proposal 1 - The Merger -
Opinion of AMRB's Financial Advisor - Comparable Company Analyses" is hereby
amended by deleting the table of company names at the top of page 52 (BMRC Peer
Group) of the joint proxy statement/prospectus and replacing it with the
following:



Financials as of December 31, 2020                                      Market Data (as of 04/15/2021)           LTM Profitability                Balance Sheet Ratios
                                                                                 Price /
                                                                            Tang.        Est.        1 Yr
                                                               Total    Mkt

 Book   LTM  2021  Div. Price      Eff.                        TCE/ Loan/ Cost of    NIBD/    NPAs/
                                                              Assets    Cap Value   EPS   EPS Yield     ?     Ratio   NIM  ROAA  ROAE        TA  Dpts   Funds Deposits   Assets
Company Name                       City, St        Ticker       ($M)   ($M)   (%)   (x)   (x)   (%)   (%)       (%)   (%)   (%)   (%)       (%)   (%)     (%)      (%)      (%)

Western Region Exchange-Traded Banks with Total Assets $2.0 - $8.0 Billion, Cost of Funds Less than 0.25%, and NIBD / Total Deposits Greater than 30%


TriCo Bancshares                   Chico, CA       TCBK        7,640  1,394

203 21.7 15.6 2.1 60.0 56 3.96 0.91 7.2 9.3 73

  0.10       40     0.44
Westamerica Bancorporation         San Rafael, CA  WABC        6,748  1,715

238 20.6 21.9 2.6 8.6 47 2.91 1.30 11.3 10.9 22

  0.03       48     0.11
Heritage Financial Corporation     Olympia, WA     HFWA        6,615  1,014

179 21.9 17.3 2.8 52.4 62 3.60 0.74 5.8 8.9 80

  0.16       35     1.46
Central Pacific Financial Corp.    Honolulu, HI    CPF         6,595    771

  141  20.7  15.8   3.4  88.9        61  3.30  0.58   6.9       8.3    86    0.16       31     0.21
Heritage Commerce Corp             San Jose, CA    HTBK        4,634    721   183  20.4  18.7   4.3  68.5        55  3.50  0.80   6.1       8.8    67    0.19       42     0.17
Sierra Bancorp                     Porterville, CA BSRR        3,221    414   132  11.6  10.5   3.1  64.6        57  3.95  1.22  10.8       9.8    94    0.13       36     0.62

Central Valley Community Bancorp   Fresno, CA      CVCY        2,004    244

128 12.0 11.8 2.3 60.3 64 3.87 1.11 8.9 9.8 64

0.07 48 0.56

Note: Institutions are not pro forma for pending / recently completed M&A and / or capital raises that occurred after period end; Excludes merger targets

Source: S&P Global Market Intelligence









3.      The disclosure under the heading "Joint Proposal 1 - The Merger -Opinion
of AMRB's Financial Advisor -Analysis of Precedent Transactions" is hereby
amended by deleting the table of Acquiror and Target names at the top of page 53
(the Precedent Transactions group) of the joint proxy statement/prospectus and
replacing it with the following:



                                                                Transaction Information                   Seller Financial Information
                                                       Consideration      Price/       Core 1-Day
                                                      Deal       Cash/    LTM Tang. Deposit Market    Total  Total TCE/    LTM   LTM  NPAs/
                                             Annc.   Value   Stock Mix   

EPS Book Prem. Prem. Assets Equity TA ROAA ROAE Assets Acquiror

                Target                Date    ($M)         (%)    

(x) (%) (%) (%) ($M) ($M) (%) (%) (%) (%)

Nationwide Bank Transactions Since March 1, 2020 with Target Assets $0.60B - $1.25B



Stock Yards Bancorp,    Kentucky
Inc. (KY)               Bancshares, Inc.    01-27-21 191.3  15% / 85%    

16.3 171 9.5 68.8 1,201 125 9.4 1.00 9.7 0.51


                        (KY)

BancorpSouth Bank (MS) FNS Bancshares, 01-13-21 108.4 17% / 83% 19.4 154 6.5 35.1 786 81 9.1 0.78 7.0 0.80


                        Inc. (AL)
                        National United
BancorpSouth Bank (MS)  Bancshares, Inc.    12-02-20 114.7  29% / 71%    15.8   156     6.8      -      749     75 10.0   1.10  10.5   1.17
                        (TX)
Virginia National       Fauquier
Bankshares Corporation  Bankshares, Inc.    10-01-20  62.2  0% / 100%    10.1    85   (1.4)    8.1      840     72  8.6   0.79   8.8   1.31
(VA)                    (VA)
First Mid Bancshares,   LINCO Bancshares,   09-28-20 144.9  80% / 20%    21.0   107     1.4      -    1,184    169 12.8   0.89   5.9   1.17
Inc. (IL)               Inc. (MO)
Blue Ridge Bankshares,  Bay Banks of
Inc. (VA)               Virginia, Inc.      08-13-20  97.3  0% / 100%    17.9    81   (2.8)   21.4    1,238    120  9.6 (0.37) (3.4)   1.38
                        (VA)


Source: S&P Global Market Intelligence; as of April 15, 2021









4.      The disclosure under the heading "Joint Proposal 1 - The Merger -

Opinion of AMRB's Financial Advisor - Net Present Value Analyses" is hereby
supplemented by adding the following to the first paragraph thereunder as a new
third sentence following the number 150% at the bottom of page 53 of the joint
proxy statement/prospectus:



Piper Sandler selected these price to earnings and tangible book value multiples
based on Piper Sandler's review of, among other matters, the trading multiples
of selected companies that Piper Sandler deemed to be comparable to AMRB.

5. The disclosure under the heading "Joint Proposal 1 - The Merger - Opinion of AMRB's Financial Advisor - Net Present Value Analyses" is hereby supplemented by adding the following table after the Earnings Per Share Multiples chart (Annual Estimate Variance) in the middle of page 54 of the joint proxy statement/prospectus:


The following table describes the discount rate calculation for AMRB common
stock prepared by Piper Sandler. In its normal course of business, Piper Sandler
employs the Duff & Phelps Cost of Capital Navigator in determining an
appropriate discount rate in which the discount rate equals the sum of the risk
free rate, the equity risk premium, the size premium and the industry premium.

Risk Free Rate 1.56 % Per Duff & Phelps Normalized Rate

Equity Risk Premium 7.15 % Per Duff & Phelps Cost of Capital Navigator



Size Premium         3.16 %  Per Duff & Phelps Cost of Capital Navigator

Industry Premium     1.29 %  Per Duff & Phelps Cost of Capital Navigator

 Discount Rate      13.16 %



6. The disclosure under the heading "Joint Proposal 1 - The Merger - Opinion of AMRB's Financial Advisor - Net Present Value Analyses" is hereby supplemented by adding the following to the last full paragraph at the bottom of page 54 of the joint proxy statement/prospectus as a new third sentence following the number 225%:



Piper Sandler selected these price to earnings and tangible book value multiples
based on Piper Sandler's review of, among other matters, the trading multiples
of selected companies that Piper Sandler deemed to be comparable to BMRC.

7. The disclosure under the heading "Joint Proposal 1 - The Merger - Opinion of AMRB's Financial Advisor - Net Present Value Analyses" is hereby supplemented by adding the following table after the Earnings Per Share Multiples chart (Annual Estimate Variance) at the bottom of page 55 of the joint proxy statement/prospectus:


The following table describes the discount rate calculation for BMRC common
stock prepared by Piper Sandler. In its normal course of business, Piper Sandler
employs the Duff & Phelps Cost of Capital Navigator and Bloomberg in determining
an appropriate discount rate in which the discount rate equals the risk free
rate plus the product of the 2-year beta for BMRC common stock and the equity
risk premium, plus the size premium.

Risk Free Rate 1.56 % Per Duff & Phelps Normalized Rate

2 Year Beta of Stock 114.2 % Bloomberg

Equity Risk Premium 7.15 % Per Duff & Phelps Cost of Capital Navigator



Size Premium          1.42 %  Per Duff & Phelps Cost of Capital Navigator

 Discount Rate       11.14 %




8.      The disclosure under the heading "Joint Proposal 1 - The Merger -Opinion
of AMRB's Financial Advisor -Pro Forma Transaction Analysis" is hereby amended
by deleting the last sentence of the first paragraph of the section at the
bottom of page 55 of the joint proxy statement/prospectus and replacing it

with
the following:



The analysis indicated the merger could be accretive to BMRC's estimated
earnings per share (excluding one-time transaction costs and expenses) in the
years ending December 31, 2022, December 31, 2023 by approximately 13.5% and
13.2%, respectively, and could be dilutive to BMRC's estimated tangible book
value per share at closing as of September 30, 2021 by approximately 3.9%,
approximately neutral to BMRC's estimated tangible book value per share at
December 31, 2024 and approximately 0.9% accretive BMRC's estimated tangible
book value per share at December 31, 2025.

9. The disclosure under the heading "Joint Proposal 1 - The Merger -Interests of Directors and Executive Officers-Continued Employment" is hereby amended on Page 76 by deleting the two paragraphs under such heading and replacing it with the following:


It is currently contemplated that certain of the senior executive officers of
AMRB may continue their employment for some period of time with BMRC and/or Bank
of Marin to assist with post-merger integration, not to extend past October 15,
2021 in the case of Messrs. Bender and Derenzo or past December 31, 2021 in the
case of Mr. Ritchie. Mr. Colombo and Mr. Ritchie communicated with each other
periodically both before and after the signing of the merger agreement regarding
post-transaction employment and directorships and successful integration of

AMRB
and Bank of Marin.



Other than as set forth above, no director or officer of AMRB has any direct or
indirect material interest in the merger, except insofar as ownership of AMRB
common stock might be deemed such an interest.

10. The following disclosure amends and supplements the discussions in the section of the Definitive Proxy Statement entitled "Joint Proposal 1--The Merger" on page 80 by adding in the following section entitled "Litigation Relating to the Merger".





On June 21, 2021, Shiva Stein, a purported shareholder of the Company at the
time which the Company and Marin Bancorp entered into the merger agreement (the
"Merger Agreement"), filed a lawsuit against the Company and the members of its
board of directors in the United States District Court for the Eastern District
of California, captioned Stein v. American River Bankshares, et al., Case No.
2:21-at-00566 (the "Stein Complaint").  On June 25, 2021, Pinchas Raul, a
purported shareholder of the Company at the time of the Merger Agreement, filed
a lawsuit against the Company and the current members of the Company's board of
directors in the United States District Court for the Southern District of New
York, captioned Raul v. American River Bankshares, et al., Case No.
1:21-cv-00565 (the "Raul Complaint").  On June 28, 2021, Matthew Whitfield, a
purported shareholder of the Company at the time of the Merger Agreement, filed
a lawsuit against the Company, the current members of the Company's board of
directors, and Marin Bancorp in the United States District Court for the
Southern District of New York, captioned Whitfield v. American River Bankshares,
et al., Case No. 1:21-cv-05607 (the "Whitfield Complaint"). On July 8, 2021,
Paul Parshall, a purported shareholder of the Company at the time of the Merger
Agreement, filed a lawsuit against the Company and the current members of the
Company's Board of Directors in the United States District Court for the Eastern
District of California, captioned Parshall v. American River Bankshares, et al.,
Case No. 2:21-at-00617 (the "Parshall Complaint"). On July 14, 2021, Jeffrey D.
Justice, II, a purported shareholder of the Company, filed a lawsuit against the
Company and the current members of the Company's Board of Directors in the
United States District Court for the Eastern District of Pennsylvania, captioned
Justice v. American River Bankshares, et al., Case No. 2:21-cv-03125 (the
"Justice Complaint", and with the Parshall Complaint, the Raul Complaint, the
Stein Complaint and the Whitfield Complaint, the "Complaints").



The Stein, Raul, Whitfield, Justice and Parshall Complaints allege that the
Company and its directors violated Section 14(a) of the Exchange Act, along with
Rule 14a-9 promulgated thereunder, by filing the registration statement of which
this document is a part, which allegedly contains false statements and omits
material information intended to solicit shareholders to vote in favor of the
merger.  The Whitfield Complaint is the only action that lists Marin Bancorp as
a defendant.  All five Complaints also allege that the directors of the Company
(and, in the case of the Whitfield Complaint, Marin Bancorp) violated Section
20(a) of the Exchange Act due to their positions as controlling persons over
parties that allegedly knowingly violated Section 14(a), and are thus liable
under Section 20(a).  The Complaints seek (1) injunctive relief preliminarily
and permanently enjoining consummation of the merger, (2) rescission of the
merger and an award of rescissory damages in the event the merger is
consummated, (3) injunctive relief directing dissemination of a registration
statement that does not contain any untrue statements of material fact and that
states all material facts in it or necessary to make the statements contained
therein not misleading, (4) a declaration that defendants violated Sections
14(a) and/or 20(a) of the Exchange Act, and (5) an award of costs incurred by
plaintiff in bringing the lawsuit, including attorneys' and experts' fees.  The
Company and Marin Bancorp believe the Complaints are without merit.  At this
stage, it is not possible to predict the outcome of the proceedings in the
merger-related litigation or their impact on the Company, Marin Bancorp or

the
merger.







Forward-Looking Statements



This communication includes forward-looking statements within the meaning of the
"Safe-Harbor" provisions of the Private Securities Litigation Reform Act of
1995. These statements are necessarily subject to risk and uncertainty and
actual results could differ materially from those anticipated due to various
factors, including those set forth from time to time in the documents filed or
furnished by the Company and Marin Bancorp with the Securities and Exchange
Commission (the "SEC"). The following factors, among others, could cause actual
results to differ from those set forth in the forward-looking statements: (i)
the possibility that the Merger does not close when expected or at all because
required regulatory, shareholder or other approvals, financial tests or other
conditions to closing are not received or satisfied on a timely basis or at all;
(ii) the businesses of the Company and Marin Bancorp may not be integrated
successfully or such integration may be more difficult, time-consuming or costly
than expected; (iii) changes in the Company's or Marin Bancorp's stock price
before closing, including as a result of its financial performance prior to
closing, or more generally due to broader stock market movements, and the
performance of financial companies and peer group companies; (iv) the risk that
the benefits from the transaction may not be fully realized or may take longer
to realize than expected, or that expected revenue synergies and cost savings
from the Merger may not be fully realized or realized within the expected time
frame, including as a result of changes in general economic and market
conditions, interest and exchange rates, monetary policy, laws and regulations
and their enforcement, the effect of pandemic disease (including Covid-19) and
the degree of competition in the geographic and business areas in which the
Company and Marin Bancorp operate; (v) the ability to promptly and effectively
integrate the businesses of the Company and Marin Bancorp; (vi) the reaction to
the transaction of the companies' clients, employees and counterparties; (vii)
diversion of time of directors, management and other employees on merger-related
issues; (viii) changes in interest rates, general economic conditions,
legislative/regulatory changes, monetary and fiscal policies of the U.S.
government, including policies of the U.S. Treasury and the Board of Governors
of the Federal Reserve; the quality and composition of the loan and securities
portfolios; demand for loan products; deposit flows; competition; demand for
financial services in the companies' respective market areas; their
implementation of new technologies; their ability to develop and maintain secure
and reliable electronic systems; and accounting principles, policies, and
guidelines, (ix) lower than expected revenues, credit quality deterioration or a
reduction in real estate values or a reduction in net earnings; and (x) other
risks that are described in the Company's and Marin Bancorp's public filings
with the SEC. You should not place undue reliance on forward-looking statements
and the Company and Marin Bancorp undertake no obligation to update any such
statements to reflect circumstances or events that occur after the date on which
the forward-looking statement is made except as required by law.



Additional Information About the Merger and Where to Find It





Investors and security holders are urged to carefully review and consider each
of the Company's and Marin Bancorp's public filings with the SEC, including but
not limited to their Annual Reports on Form 10-K, their proxy statements, their
Current Reports on Form 8-K and their Quarterly Reports on Form 10-Q. The
documents filed by the Company with the SEC may be obtained free of charge at
the Company's website at www.americanriverbank.com or at the SEC's website at
www.sec.gov. These documents may also be obtained free of charge from the
Company by requesting them in writing to American River Bank, 3100 Zinfandel
Drive, Rancho Cordova, California 95670; Attention: Corporate Secretary, or by
telephone at 916-851-0123. The documents filed by Marin Bancorp with the SEC may
be obtained free of charge at Marin Bancorp's website at www.bankofmarin.com or
at the SEC's website at www.sec.gov. These documents may also be obtained free
of charge from Marin Bancorp by requesting them in writing to Bank of Marin
Bancorp, 504 Redwood Boulevard, Suite 100, Novato, California 94947 or by
telephone at (415) 763-4520.



Marin Bancorp has filed a registration statement with the SEC (333-257025) which
includes a joint proxy statement of the Company and Marin and a prospectus of
Marin, and each party will file other documents regarding the proposed
transaction with the SEC. Before making any voting or investment decision,
investors and security holders of the Company and Marin are urged to carefully
read the entire registration statement and joint proxy statement/prospectus as
well as any amendments or supplements to these documents, because they will
contain important information about the proposed transaction. A definitive joint
proxy statement/prospectus has been sent to the shareholders of the Company and
Marin Bancorp seeking required shareholder approvals. Investors and security
holders are able to obtain the registration statement and the joint proxy
statement/prospectus free of charge from the SEC's website or from the Company
or Marin Bancorp by writing to the addresses provided for each company set

forth
in the paragraphs above.



The Company, Marin Bancorp, their respective directors, executive officers and
certain other persons may be deemed to be participants in the solicitation of
proxies from the Company and Marin shareholders in favor of the approval of the
transaction. Information about the directors and executive officers of the
Company and their ownership of Company common stock is set forth in the proxy
statement for the Company's 2021 annual meeting of shareholders, as previously
filed with the SEC. Information about the directors and executive officers of
Marin Bancorp and their ownership of Marin Bancorp common stock is set forth in
the proxy statement for Marin Bancorp's 2021 annual meeting of shareholders, as
previously filed with the SEC. Shareholders may obtain additional information
regarding the interests of such participants by reading the registration
statement and the joint proxy statement/prospectus when they become available.

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