Fannie Mae is implementing a new policy this week regarding home appraisals. Beginning Wednesday, lenders will be prohibited from making changes to appraisers' valuations - a practice that has become more widespread and is commonly referred to as "appraisal cutting." Fannie officials say they have identified cases where the lender reduced the opinion of market value in the appraisal report based upon underwriter judgment or automated valuation models, prompting the GSE to place a ban on so-called appraisal cutting.