Academic studies and practitioner literature agree that investment performance deteriorates as fund size increases. While useful in principle, all of these studies are based on analysis of fund returns, which gives investors little insight on how to translate this finding into action. In fact, it is well known that fund returns poorly represent the strengths or weaknesses of the underlying investment process. At what point is AUM growth excessive? What are the leading indicators that such growth is having a detrimental impact on the investment process? What data can investors use to build predictive indicators of deteriorating returns?