Common trust fund to be audited annually.

A trust company or trust department administering a common trust fund shall keep proper records, which in addition to all other necessary and proper matters shall show at all times the proportionate interest of each fiduciary account in the common trust fund, and, at least once during each period of 12 months, shall cause an audit to be made of the common trust fund by auditors responsible only to the board of directors of the trust company or trust department. The report of such audit shall include a list of the investments comprising the common trust fund at the time of the audit, which shall show the valuation placed on each item on such list by the board of directors or the trust investment committee of the trust company or trust department as of the date of the audit; a statement of purchases, sales, and any other investment changes and of income and disbursements since the last audit; and appropriate comments as to any investment in default as to payment of principal or interest. The reasonable expenses of any such audit made by independent public accountants may be charged to the common trust fund. The bank, association, or trust company shall manage such common trust funds without charge, save necessary expenses, and it shall send a copy of the latest report of such audit annually to each person to whom a regular periodic accounting of the fiduciary accounts participating in the common trust fund ordinarily would be rendered or shall send advice to each such person annually that the report is available and that a copy will be furnished without charge upon request.