Bank of America’s decision to waive the attorney-client privilege in New York Attorney General Andrew Cuomo’s probe into bonus payments made by Merrill Lynch after its acquisition by the bank reflects both a change in tactics and tone.

The cordial letter sent Monday by Bank of America attorney Lewis J. Liman to David A. Markowitz of the attorney general’s Investor Protection Unit stands in marked contrast to the public fight between the two last month over assertion of the privilege.