The market right now is highly manipulated, the plaything of a few institutional players. The mega-banks.
With Glass-Steagall gone, and with ZIRP at the Fed Discount window, the banksters are pouring OPM into the stock markets...paying themselves commissions and buying without discretion.
At some point, since they are a small number and represent the bulk of the low-levels of trading going on...at some point, by some signal they'll understand, they will sell, more-or-less in unison. Could happen in a "Flash Crash" as we've seen; or it could happen in a more orderly way...over the course of a day or a week. But it will happen; and the Muppet investors will be left out to dry.
The fundamentals don't reflect the stock prices in most cases. Earnings are down, in some cases there's heavy losses. JCPenney and Sears have shown multiyear losses; but each time they rearrange the players, with a new Fix-It CEO or new Five-Year Plan...their stock prices go UP.
So for HSBC to say the market will tank, is not a prediction. It's a statement of their intentions.