Now that the US has put out a notice for auction of 50000 BTC, i see big investors and whales dumping to bring down the price so that they can buy in cheap and pickup those 50K coins. Something similar to what happened when they announced the sale the last time.
The price rose, for as-yet unknown reasons, from ~450$ on May-20 to ~650$ on Jun-03, and held there for a few days,
On Jun-12 the USMS announced the auction of the SR coins. The price immediately fell ~70$, and wandered about ~580$ until the auction. It was ~600$ on auction day, Jun-29.
On the next day, Jun-30, the price jumped up again to about ~650$. However it started to decline gradually, and by the end of July it was back to ~580$.
The drop after the announcement may have been manipulation, as claimed above. However it could have been due to general fear that the auctioned coins would end up being sold on the open market, and/or that the auction would close well below market.
The recovery on Jun-30 would then be due to the news that all coins had been bought by a ingle bidder. Most people inferred, rightly or wrongly, that his bid had been well above market, and therefore that he was optimistic about the long term, and therefore he would not be dumping those coins on the exchanges. (Anyone recalls when exactly Draper came public?)
Is the current slump related to the new USMS auction? The times do not seem to match, and the impact of this new auction's announcement has been nothing compared to that of the June one.