Over the weekend, the following happened: China's exports and imports fell by 11.2% and 18.8%, respectively, numbers which, for a trading power, are nothing short of apocalyptic. Japan's Q4 GDP shrank at an annualized rate of 1.4% which, for a country that had spent the previous three years borrowing and printing record amounts of new currency, is an extraordinary admission of failure. And US allies Turkey and Saudi Arabia appeared to be invading Syria, putting them -- and by implication the US -- in direct confrontation with Russia.

This combination of disturbing trends and events would, you'd think, produce a dark and chaotic opening for Monday's global financial markets. But you'd be wrong, because while the above was going on, Mario Draghi, head of the European Central Bank announced that he "will not hesitate to act" to stop the past month's carnage. And traders responded the way they've been trained to, with panic buying of pretty much every dicey financial asset and panic selling of safe havens like gold, Treasury bonds and euros.

This came after previous attempts by central banks -- including China's yuan devaluation and Japan's foray into negative interest rates -- failed to get the markets' juices flowing. So why did Draghi have the opposite effect? Three reasons:

1. He has a history of this kind of thing. Recall his 2012 "whatever it takes" promise that ignited the most recent leg of the global asset bubble. So despite the fact that he doesn't actually do much, traders seem to find the ex-Goldman Sachs bankers words inordinately comforting.

2. One of the things Draghi seems to be offering this time around is expanded help for Italy's imminent banking system implosion. 18% of Italian bank loans are "non-performing," that is, not making payments. This is almost without precedent for a whole country and extremely rare for individual banks -- usually the latter die before things reach this point. So if the ECB changes the rules to, for instance, allow Italian banks to use non-performing loans as collateral for new financing, that might keep them alive for a little while longer. Though at the cost of vastly increased taxpayer liabilities.

   Traders of course don't care about vague notions of future obligations, assuming that they'll be inflated away or otherwise forgiven by some future Super Mario. So the prospect of bank bailouts is, to them, an unalloyed good thing.

3. It was time for a counter-trend rally. The first six weeks of 2016 were among the worst starts to a year ever for stocks and junk bonds (and among the best ever for safe havens like Treasuries and gold). Trends don't go in a straight line; instead they take two steps forward and one step back, repeating those dance steps until the cycle ends. So traders were waiting for an excuse to buy suddenly- cheap bank and tech stocks.

Based on past experience, the pop might endure for another few days or even weeks. But then the abject failure of past central bank experiments will once again start to color perceptions. To take just a couple of examples: Four years after Draghi's "whatever it takes" boast, Italy, as previously mentioned, is imploding and Deutsche Bank, Germany's dominant financial institution, is releasing a drumbeat of bad/ominous news including escalating losses, massive lay-offs and flat-lining divisions. It's even being mentioned in the same breath as Lehman Brothers.

Japan, meanwhile, offers a useful clue about the effectiveness of whatever the ECB and for that matter the Fed might try next. The money it has pumped into the economy, as measured by central bank assets -- the bonds and stocks it has bought with newly-created yen -- rose from 25% of GDP in 2007 to nearly 80% today. But the Japanese economy has gone exactly nowhere. For a great recap of the wasted effort that is QE, see $12.3 trillion of QE has added up to...this?

In short, the limits of this kind of monetary policy are now visible for all to see. Despite differing levels of ease, all the major economies are behaving pretty much the same way, with slow to slightly-negative growth, steadily increasing debt, and spiking asset price volatility. More of the same is unlikely to change that.

So...what next? A brief respite from "risk-off" followed by the resumption of turmoil (financial, geopolitical or both). Into this breach will step the US Fed because, as Deutsche Bank noted today, only the Fed can do it:

Only the Fed can save stocks now: Deutsche Bank

(CNBC) - The prolonged sell-off in risk assets across the globe will only abate if the U.S. Federal Reserve changes its path and begins to loosen its monetary policy once again, according to strategists at Deutsche Bank.

Chinese growth fears, stress in the U.S. energy sector and fragile balance sheets in European financial companies have all been credited in the last week for fueling the sell-off. However, there's only one real cure for this current bout of weakness, according to a team of European equity analysts at the German bank, led by Sebastian Raedler.

"Without policy intervention, there is more downside risk for equities," the bank said in a note entailed "The smell of default" on Monday.

A major focus for the analysts has been rising bond yields on riskier corporate debt in the U.S.. This has been seen as a sign of an end of the current credit cycle, which in turn could that could pave way for a number of defaults in the country, the bank noted. Raedler said that U.S. high-yield spreads - the difference between investment grade and non-investment grade bonds - have risen above their 2011 peak and warned of the potential for a self-fulfilling "full default cycle." He highlighted the stress had started with energy firms - that have been hit by the oil price plunge - but added that it wasn't confined to this sector.

"To avoid a further rise in U.S. defaults, we will likely need to see a Fed relent, leading to a sustainable drop in the dollar, higher oil prices and reduced energy balance sheet stress," the bank said in the report.

The problem for investors is that there is little sign of the Fed wanting to change course, Raedler added. Data last week from the Bureau of Labor Statistics showed that U.S. firms were continuing to hire with 5.6 million job openings in December 2015, up from 5.43 million job openings in November.

Rather than cutting, these data are likely to leave the U.S. central bank on course for more rate hikes after it decided to tighten policy at its December meeting last year. However, Fed Chair Janet Yellen sounded a more cautious tone in her testimony to Congress on Thursday.

Equities have been roiled this year with the pan-European Euro Stoxx 600 index down 12 percent and the S&P 500 already losing nearly 9 percent, both on course for their worst year since the 2008 financial crisis. Deutsche Bank shares have been at the forefront of the selling in Europe with questions raised over the quality of its balance sheet.

A "full default cycle" in the U.S. would trigger a further 20 percent downside European equities, Raedler said, but would also increase the risk of a U.S. recession. He believes that this rising cost of debt for corporates would reduce their spend on investment and hiring. Falling equity prices would also urge people to save and thereby dent consumption growth, he added.