Definition of highly confident letter

letter from an investment banking firm that it is "highly confident" that it will be able to arrange financing for a securities deal. This letter might be used to finance a leveraged buyout or multibillion-dollar takeover offer, for example. The board of directors of the target firm might request a highly confident letter in evaluating whether a proposed takeover can be financed. After the letter has been issued and the deal approved, the investment bankers will attempt to line up financing from banks, private investors, stock and bond offerings, and other sources. Though the investment banker professes to be highly confident he can arrange financing, the letter is not an ironclad guarantee of his ability to do so.