According to a weekly report released by Coinbase on Friday, bitcoin has underperformed the S & P 500 index since the deleveraging event in early August. "On a risk-adjusted basis, bitcoin is now 0.50 standard deviations below its three-month average, while the S & P 500 is actually 1.41 standard deviations above its three-month average," said Coinbase analysts David Duong and David Han. Coinbase analysts said that bitcoin's recent price performance has been volatile, with a fairly narrow trading range, a lack of narrative catalysts to drive bitcoin prices higher, and September being a seasonally difficult time for cryptocurrencies.