Filed by Wintrust Financial Corporation
                                                  (Commission File No.  0-21923)
                                                  pursuant to Rule 425 under the
                                              Securities Act of 1933, as amended

                               Subject Company: Advantage National Bancorp, Inc.

          ADVANTAGE NATIONAL BANCORP, INC. MAILED THE FOLLOWING LETTER,
                    DATED JULY 2, 2003, TO ITS SHAREHOLDERS:


                  [ADVANTAGE NATIONAL BANCORP, INC. LETTERHEAD]

         July 2, 2003


         Dear Shareholders and Friends,

         Two and a half years ago you placed your faith in us when you became a
         shareholder in a new banking venture. We were gratified by your
         response then, and are immensely pleased to report to you now that your
         investment was both a wise one and a profitable one.

         Advantage National Bank has exceeded our expectations and projections;
         we have grown to over $100 million in assets and over $75 million in
         loans while achieving profitability each month over the past year. This
         positive growth has come despite the low interest rate environment, the
         terrible tragedy of September 11, the war in Iraq, and the downturn in
         the general economy.

         Although it was our original intent to grow the business as an
         independent community bank, your board has recently signed a merger
         agreement allowing us to join forces with a consortium of local
         community banks. Under this agreement, Wintrust Financial Corporation
         (Wintrust), a holding company that currently owns seven community banks
         with 32 locations throughout the suburbs of Chicago, will acquire
         Advantage National Bancorp, Inc. and become its parent corporation. By
         merging with Wintrust, we believe we will be able to grow the bank at a
         faster pace, expand our lending capacity without the need to sell
         additional stock, offer new products and services to our customers, and
         create liquidity for the stock of our investors.

         Wintrust is an 11 year-old organization that established all seven of
         its existing banks as new charters, just like we did with Advantage
         National Bank. However, each bank retains its own name, selects its own
         staff, and makes local decisions based on the needs of that bank's
         individual community. Employing these business principles, Wintrust has
         achieved assets in excess of $3.9 billion in this relatively short
         period of time, while also achieving solid growth in profitability.
         Through the merger agreement, Advantage National Bancorp, Inc. (parent
         corporation of Advantage National Bank) will be the first bank to join
         the Wintrust organization through acquisition.




         Like the other Wintrust banks, we expect Advantage National Bank will
         retain its name, personnel, and board of directors. The bank will
         continue to operate and service its customers without changing
         management or staff while expanding its community presence. Most
         importantly, we will remain committed to local decision-making and
         efficient personal service--the business practices that allow us to
         best service our clients and communities. Our goal, a goal shared and
         endorsed by Wintrust, is to remain a strong community bank with service
         and product capabilities of a much larger organization. We believe this
         is what our customers both desire and need.

         Now, here is the good news for you, our shareholder. As part of this
         proposed transaction, we will exchange our existing shares of stock for
         shares of Wintrust with a value of $26.50 per share. For our
         shareholders who purchased Advantage National Bank shares at $15.00
         each in our (2000) offering, this translates into a net profit of
         $11.50 per share or a net return of over 75 % on your initial
         investment. Moreover, if the merger is completed, you will own shares
         in Wintrust, a publicly traded company listed on the NASDAQ Stock
         Market under the ticker symbol "WTFC." This means you'll have the
         ability to sell your stock at any time through a brokerage firm and
         convert your investment to cash, or you may do as many of us will and
         hold on to your new shares as an investment vehicle in the dynamic
         Wintrust organization.

         The completion of this transaction is subject to receipt of various
         regulatory approvals as well as the endorsement of our shareholders at
         a special meeting to be held within the next few months. Between now
         and then, we will provide you with the necessary detailed information
         regarding the proposed merger and how it affects you. We believe that
         this move will allow Advantage National Bank to continue operating as a
         locally controlled community bank, will allow shareholders to realize a
         substantial return on their investment, and will allow customers access
         to expanded services through the Wintrust organization.

         We are enclosing with this letter a copy of the press release
         announcing the proposed merger. If you have any questions about this
         transaction, please call any of your directors.

         We appreciate your continued support--past, present and future.



         Gary E. Umlauf                              Keith J. Kotche
         Chairman, Advantage National Bank           Chairman, Advantage
                                                     National Bancorp, Inc.

         encl: press release announcing the merger





ADDITIONAL INFORMATION

Wintrust will be filing a registration statement with the Securities and
Exchange Commission in connection with the proposed transaction. The
registration statement will include a proxy statement/prospectus that will be
sent to the shareholders of Advantage National Bancorp, Inc. seeking their
approval of the proposed transaction.

Shareholders of Advantage are advised to read the important information
concerning the proposed transaction contained in the proxy statement/prospectus
and other documents filed by Wintrust with the Securities and Exchange
Commission when they become available. When filed, these documents, can be
obtained free of charge from the web site maintained by the Securities and
Exchange Commission at http://www.sec.gov. or upon written request to Wintrust
Financial Corporation, Attn: Investor Relations, 727 North Bank Lane, Lake
Forest, Illinois 60045 or by calling (847) 615-4096, or upon written request to
Advantage National Bancorp, Inc., Attn: President, 75 East Turner Avenue, Elk
Grove Village, Illinois 60007 or by calling (847) 364-0100.