Alternative Risk Premia (ARP) are rule-based strategies. They should reward investors exposed to non-traditional systematic risk factors. Yet, allocation to ARP is not straightforward. First, there are many ARP indices proposed by different providers that claim to capture the same underlying risk premia. Second, a proposed index may not automatically mimic an existing risk premium whose performance is sustainable or persistent. Our findings confirm these suspicions.If some categories of indices show risk-return characteristics that are rather homogeneous, others are highly heterogeneous. Stated otherwise, performance is provider dependent making the choice of an index an important component of the allocation process. Differences between simulated past results and live data are then calculated. Results are indisputable. There is a significant overfitting bias. Once launched, the performance of ARP indices dropped significantly. To summarize, this research paper shows that investors should take no short cuts.When it comes to allocating capital to ARP, an extensive due diligence process is required.Electronic copy available at: https://ssrn.com/abstract=3045057 3 Alternative Risk Premia (ARP) are better understood when compared to traditional long-only risk factors. Everyone investing in financial securities as equities or bonds is indeed aware that capital is at risk and that it is this same risk that calls for the existence of "risk premia". The idea behind ARP is the same. Investors must be rewarded for the risk they take. The difference comes from the way the exposure is achieved. ARP are non-traditional risk factors and roughly speaking correspond to any long-short strategies or styles whose risk is a priori not diversifiable. Examples could be FX carry, Interest Rate (IR) carry or equity size.ARP have experienced an increase in popularity recently, among both researchers and investors.Size-wise, the ARP market still looks small compared to the hedge fund industry whose assets under management (AuM) estimates are close to $3 trillion, but new indices are continuously created and AuM are increasing. 1 According to CitiGroup, the ARP market accounted for a tiny $15 billion in 2011. By the end of 2015 it had risen to $241 billion. 2 Yet, there is nothing new in the idea that returns of risk assets can be expressed with a set of limited factors, whatever the name we want to give them. Single-factor or multi-factor return generating processes can be found in articles published as early as the sixties and seventies. One can cite, for example, the paper of Sharpe [1964] and the use of a diagonal model or the seminal article of Ross [1976] and the contribution of his Arbitrage Pricing Theory to modern finance. However, when it comes to multi-factor pricing models, one often points to the article of Fama and French [1993] in which size and book-to-market were added to a "market" factor to explain returns on equities. Since then, other factors have been proposed. The work of Jegadeesh and Titman [1993] led Cahart [19...