Who are the criminals here?
I’m not a big fan of hoaxes, but the Whitehaven coal hoax (or rather, the reaction to it) has certainly provided plenty of teachable moments. Media stories are still calling it a $300 million hoax (while throwing stones at online reporting H/T Megan), and suggesting that Mums and Dads are big losers. Now we have some actual data, showing that clients of Morgan Stanley and Macquarie gained from the trades made during the hoax while those of Citigroup and UBS lost. 
Given the claim that hoaxes like this might destroy faith in the stock market, it’s worth looking at the track record of some of these banks. Looking just at the last few months, we have:
UBS in particular has a rap sheet so long that Bloomberg news recently published a call for it to be shut down
By comparison with these global titans, Macquarie Bank looks pretty good, despite being well-known as a sharp-elbowed practitioner of regulatory arbitrage
Regulator eyes millionaires factory
It’s now clear that this systematic criminality is part and parcel of modern financial markets, and that nothing can or will be done about it. After HSBC got a slap on the wrist for a long-term money laundering operation on behalf of drugdealers, dictators and terrorists, the US Department of Justice openly admitted that the big banks are not only too big to fail, but too important to be subject to the law. Modest fines are just a cost of doing business, exactly as they are for other businesses that routinely operate at the edge of, or outside the law.
Perhaps the clients of these firms are unaware of these facts. If so, this event might help to inform them. If not, they can scarcely complain about something as trivial as a hoax press release.
fn1. Apparently Morgan Stanley bought about $2.6 million of shares, which would imply a profit of around $500k, a significant sum, but several orders of magnitude below the $300 million quoted