Thanks for your reply.
The linked article, however, lists the days with the largest UPpity in price. As if I were to sell on the same day.
What is the best day to buy Bitcoin?
Over the years, Saturday has emerged as the best day of the week to buy Bitcoin, with the coin gaining 0.413% on average on that day. According to historical data, Monday is the second-best day to buy Bitcoin due to an average increase of 0.360%. Friday is the only day of the week that Bitcoin has shown negative growth over the years.
Interestingly, out of the 50 biggest single-day spikes in the last 7 years, 10 occurred on Thursday, 9 each on Tuesday and Wednesday, 7 each on Monday and Saturday, 5 on Friday, and only 2 on Sunday.
What I'm looking for - and haven't yet been able to find - is the day with the average lowest price in the week.