We analyze the effect of alternative data on the informativeness of financial forecasts. Our hypothesis is that the emergence of alternative data increases the net benefit of collecting short-term information about firms' cash flows more than the benefit of collecting long-term information. If this hypothesis is correct, and forecasting short-term and long-term cash flows are distinct tasks, alternative data should make short-term forecasts more informative but long-term forecasts less so. We confirm this prediction empirically for sell-side equity analysts' forecasts using a new measure of forecast informativeness at various horizons.