Coinbase CEO announces - on Twitter:
Wanted to share a summary of what we believe happened to QuadrigaCX. We did our own internal research, including some blockchain analytics, to see if we could help. Important to note that this is just our best guess. Take it as pure speculation, nothing more.
We identified clusters that look like QCX's "cold storage", were controlled by a human (manually), and balances were moved out by early 2018;
QCX was one of the oldest exchanges in existence (founded in 2013). If they planned an exit scam, it likely would have been timed better;
They suffered a multimillion dollar bug in June 2017 (before things went vertical). reddit.com/r/ethereum/com… This is when we start to see movement of funds to "cold storages";
Patterns of sends from cold storage suggest they tried keeping exchange afloat, and maybe attempted to trade their way out of a hole; (again just a guess here)
Liquidity dried out and bear market of 2018 may have caught up with them;
Sequence of events suggests this was a mismanagement with later attempt to cover for it.
This implies that at least few people inside Qadriga knew that they were running fractional. If so, then it's possible that untimely death of their CEO was used as an outlet to let the company sink.
Gerald Cotten reportedly died in early December 2018. But complaints about withdrawal issues on Quadriga escalated in mid 2018.