From a strictly mathematical point of view, the accounting-based equity valuation model is impervious to accounting manipulations under the clean surplus relation. Firms that overstate net income will have higher book values, which will reduce future residual income. Firms with conservatively measured net income will report lower book values, which will increase future residual income. On the other hand, projections of future profitability are based on current and past financial results. To the extent that accounting manipulations can affect net income forecasts by users, these manipulations will affect firm valuation.