Whenever the losses of a credit union, resulting from a depreciation in value of its loans or investments or otherwise, exceed its undivided earnings and reserves so that the estimated value of its assets is less than the total amount of share accounts and membership shares and the board of directors determines that the credit union may be subject to involuntary liquidation, the board may propose a reduction in shares. The credit union may, by a majority vote of those voting on the proposition, with the approval of the department, order a reduction in the membership shares and share accounts of each of its shareholders to divide the loss in proportion to the shareholdings held by shareholders in their respective share accounts with such terms as the department may prescribe.