None of the stories in Cointelegraph's Analysis category attempted to explain the drop at the beginning of the month.
Here's a similar chart showing just the week when the drop occurred. For the record, 5 September was a Wednesday.
It's not a very good chart. The only prices shown are from the midpoint of each day (noon?, GMT?) and are connected with a straight line. The first story I read about the drop was from CNBC:-
- 2018-09-05: Bitcoin falls after Goldman reportedly drops crypto trading plans (cnbc.com; 'Published 9:00 AM ET Wed, 5 Sept 2018 Updated 4:50 PM ET Wed, 5 Sept 2018') 'Bitcoin slipped below $7,000 Wednesday after a report that Goldman Sachs is abandoning plans to open a trading desk for cryptocurrencies. Goldman still sees the regulatory environment as ambiguous, according to Business Insider, which cited people familiar with the matter.'
By coincidence, the second story I read was from Business Insider:-
- 2018-09-05: Bitcoin price: Cryptocurrencies drop suddenly with no explanation (businessinsider.com; Sep. 5, 2018, 4:09 PM) 'Cryptocurrency prices plunged across the board suddenly and sharply Wednesday morning, seemingly with no clear reason. Having been steady at about $7,350 a coin during most of trading during both Asian and European morning hours, bitcoin lost more than $200 in mere minutes starting about 5:50 a.m. ET, or 10:50 a.m. BST.'
Both stories, from CNBC and from Business Insider, pointed to another story from Business Insider:-
- 2018-09-08: Goldman Sachs is ditching near-term plans to open a bitcoin trading desk, instead focusing on a key business for driving Wall Street investment in crypto (businessinsider.com; Sep. 8, 2018, 2:49 PM)
Note that the 'earlier' story is dated three days after the 'later' stories. There is probably a good explanation for this, but I can't think of one. The CNBC story has a detailed price chart showing a steady price followed by two sharp drops: one just before 6 AM (EDT) and another at 7 PM. It's hard to believe that unconfirmed news about a single trading desk could cause such a sudden price shift, but what do I know? Then there was another sharp drop into the following day. I wonder what caused that.