Note: This analysis was originally published on November 24th, 2016. It does not consider data from November 25th and beyond, so conclusions drawn may be outdated.past performance does not necessarily predict future results.
The most relevant data from the past six months tells us that Saturday experiences the highest percentage growth for Bitcoin with an average increase of +3.685%. Saturday has a median daily weighted price of 540.1 USD (graph*) and a median low of 526.9 USD (graph*). The worst day is Thursday with -0.04% average loss. Thursday is the only day that statistically averages a decline in Bitcoin price. Assuming that this historical data also predicts future trends, the best days to buy Bitcoin is Thursday, when the price is the lowest. The buyer has a greater-than 50% chance of seeing a profit in the next 2 days if he purchases on a Thursday. Friday and Saturday might also represent the worst days for trading altcoins due to a bullish Bitcoin trend, although an analysis should be conducted to test this hypothesis.
*(Data from Bitstamp daily data, since April 28th 2014.)