JPMorgan Global Market Strategist Jack Manley and research analyst Sahir Kauba have released a report, "Do Cryptocurrencies Deserve a Place in Portfolio Construction?", which points out that much of the appeal of cryptocurrencies lies in their potential for excess returns, but even so, challenges remain. While Bitcoin's returns are impressive, volatility is also very high, four times that of the S & P 500 Index. The role of cryptocurrencies in portfolio construction is largely determined by risk tolerance. Cryptocurrencies are inherently unpredictable: there is little visibility into future price movements, and blockchain technology, while exciting, has few barriers to entry, meaning that tokens can become obsolete (and therefore worthless) as new tokens with improved functionality enter the market. Therefore, for most investors, any allocation to cryptocurrencies in a portfolio should be kept small enough to ensure that it does not undermine overall portfolio objectives and achieve good diversification even in the event of a significant sell-off.